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物种起源|The Origin of Species

第九章　论地质记录的不完全|CHAPTER IX　ON THE IMPERFECTION OF THE GEOLOGICAL RECORD

属类： 双语小说 【分类】其他读物 阅读：[7136]
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论今日中间变种的不存在——论灭绝的中间变种的性质及其数量——从沉积速率和剥蚀速率来推算时间的经过——古生物标本的贫乏——地质层的间断——在任何一个地质层中中间变种的缺乏——物种群的突然出现——物种群在已知的最下化石层中的突然出现

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On the absence of intermediate varieties at the present day—On the nature of extinct intermediate varieties; on their number—On the vast lapse of time, as inferred from the rate of deposition and of denudation—On the poorness of our palaeontological collections—On the intermittence of geological formations—On the absence of intermediate varieties in any one formation—On the sudden appearance of groups of species—On their sudden appearance in the lowest known fossiliferous strata

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第六章列举了对于本书所持观点的主要异议。异议大多数已经讨论过了。其中之一，即物种类型的区别分明以及物种没有无数的过渡环节把它们混淆在一起，是显而易见的难点。我曾举出理由来说明，为什么这些环节今日在显然极其有利于它们存在的环境条件下，也就是说在具有渐变的物理条件的广大而连续的地域上，通常并不存在。我曾尽力阐明，每一物种的生活更关键是取决于其他已经明确的生物类型，而非气候，所以具有真正支配力量的生活条件并不像热度湿度那样不知不觉地级进消失。我也曾尽力阐明，由于中间变种的存在数量比它们所连接的类型为少，在进一步的变异改进的过程中，一般要被淘汰和消灭。然而无数的中间环节目前在整个自然界中没有到处发生，主要原因当在于自然选择这一过程，因为通过这一过程新变种不断地代替消灭了它们的亲类型。正因为这种灭绝过程曾经大规模地发生作用，地球上既往生存的中间变种一定是大规模存在的。那么，为什么在各地质层（geological formation）和各地层（stratum）中没有充满这种中间环节呢？地质学的确没有揭示任何这种微细级进的生物环节；这大概是反对我的理论的最明显、最重要的异议，我相信地质记录的极度不完全可以解释这一点。

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In the sixth chapter I enumerated the chief objections which might be justly urged against the views maintained in this volume. Most of them have now been discussed. One, namely the distinctness of specific forms, and their not being blended together by innumerable transitional links, is a very obvious difficulty. I assigned reasons why such links do not commonly occur at the present day, under the circumstances apparently most favourable for their presence, namely on an extensive and continuous area with graduated physical conditions. I endeavoured to show, that the life of each species depends in a more important manner on the presence of other already defined organic forms, than on climate; and, therefore, that the really governing conditions of life do not graduate away quite insensibly like heat or moisture. I endeavoured, also, to show that intermediate varieties, from existing in lesser numbers than the forms which they connect, will generally be beaten out and exterminated during the course of further modification and improvement. The main cause, however, of innumerable intermediate links not now occurring everywhere throughout nature depends on the very process of natural selection, through which new varieties continually take the places of and exterminate their parent-forms. But just in proportion as this process of extermination has acted on an enormous scale, so must the number of intermediate varieties, which have formerly existed on the earth, be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection which can be urged against my theory. The explanation lies, as I believe, in the extreme imperfection of the geological record.

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第一，应当永远记住，根据我的理论，何种中间类型肯定是既往生存过的。观察任何两个物种时，我难免要想象到直接介于它们之间的那些类型。但这是完全错误的观点；我们应当总是追寻介于各个物种及其共同的，但是未知的祖先之间的类型；而祖先一般在某些方面不同于全部变异后代。举一个简单的例证：扇尾鸽和球胸鸽都是从岩鸽传下来的；如果掌握了所有曾经生存过的中间变种，我们就会掌握这两个品种和岩鸽之间各有一条极其绵密的系列，但是没有任何变种是直接介于扇尾鸽和球胸鸽之间的。例如，结合这两个品种的特征——稍微扩张的尾部和稍微增大的嗉囊——的变种，是没有的。而且，两个品种已经变得如此不同，如果我们不知道有关其起源的任何历史的和间接的证据，而仅仅根据其和岩鸽在构造上的比较，就不可能去决定它们究竟是从岩鸽传下来的呢，还是从其他某一近似类型皇宫鸽（C. oenas）传下来的。

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In the first place it should always be borne in mind what sort of intermediate forms must, on my theory, have formerly existed. I have found it difficult, when looking at any two species, to avoid picturing to myself, forms directly intermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons have both descended from the rock-pigeon; if we possessed all the intermediate varieties which have ever existed, we should have an extremely close series between both and the rock-pigeon; but we should have no varieties directly intermediate between the fantail and pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified, that if we had no historical or indirect evidence regarding their origin, it would not have been possible to have determined from a mere comparison of their structure with that of the rock-pigeon, whether they had descended from this species or from some other allied species, such as C. oenas.

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自然的物种也是如此，如果观察很不相同的类型，如马和貘（tapir），我们就没有理由可以假定直接介于它们之间的环节存在过，但可以假定马或貘和未知的共同祖先之间存在过环节的。共同祖先在整个体制上与马和貘具有极其普遍的相似；但某些个别构造上可能和两者有很大的差异，甚至超越两者之间的彼此差异。因此，在所有这种情形里，除非我们同时掌握了一条近于完全的中间环节链，否则哪怕将祖先的构造和它的变异后代加以严密的比较，也辨识不出任何两个物种以上的亲类型。

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So with natural species, if we look to forms very distinct, for instance to the horse and tapir, we have no reason to suppose that links ever existed directly intermediate between them, but between each and an unknown common parent. The common parent will have had in its whole organisation much general resemblance to the tapir and to the horse; but in some points of structure may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases, we should be unable to recognise the parent-form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links.

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根据我的理论，两个现存类型中的一个来自另一个大概是可能的。例如马来自貘；这样，应有直接的中间环节曾经存在于它们之间。但是这种情形意味着一个类型极长期保持不变，而其子孙却发生了大量的变化；而生物与生物之间的竞争与亲子竞争原理将会使这种情况极少发生；因为，在所有情形里，改进的新生物类型都倾向于淘汰未改进的旧类型。

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It is just possible by my theory, that one of two living forms might have descended from the other; for instance, a horse from a tapir; and in this case direct intermediate links will have existed between them. But such a case would imply that one form had remained for a very long period unaltered, whilst its descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; for in all cases the new and improved forms of life will tend to supplant the old and unimproved forms.

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根据自然选择学说，一切现存物种都曾经和本属的亲种有联系，差异并不大于今日我们看到的同一物种的变种之间；这些目前一般已经灭绝了的亲种，同样又和更古老的物种有联系；如此反复回溯，总是会汇聚到每一个大纲（class）的共同祖先。所以，所有现存物种和灭绝物种之间的中间过渡环节的数量，必定不计其数。假如这一学说是正确的，那么这些环节必曾在地球上生存过。

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By the theory of natural selection all living species have been connected with the parent-species of each genus, by differences not greater than we see between the varieties of the same species at the present day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient species; and so on backwards, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great. But assuredly, if this theory be true, such have lived upon this earth.

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论时间的经过。——除了未发现这样无限数量的中间环节的化石遗骸之外，另有一种反对意见认为，变化既然都是通过自然选择缓慢达到的，就没有时间足以完成如此大量的生物变化。如果读者不是地质学者，我几乎不可能使他领会一些事实，从而对时间经过有所了解。赖尔爵士的《地质学原理》（Principles of Geology）将被后世历史学家承认在自然科学中掀起了一场革命，凡是读懂这部大著作的人，如果不承认过去时代曾是何等久远，还是立刻把拙作收起来吧。只研究《地质学原理》、阅读不同观察者关于各地质层的专门论文，而且注意到各作者怎样试图对于各地质层，乃至各地层的持续时间提出的不妥概念，还是不够的。必须亲自考察层层相叠的地层，仔细观察大海如何碾碎古老的岩石，进行新的沉积，才能指望对过去的时间有所了解，而这时间的一分一秒在我们的周围比比皆是。

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On the lapse of Time.—Independently of our not finding fossil remains of such infinitely numerous connecting links, it may be objected, that time will not have sufficed for so great an amount of organic change, all changes having been effected very slowly through natural selection. It is hardly possible for me even to recall to the reader, who may not be a practical geologist, the facts leading the mind feebly to comprehend the lapse of time. He who can read Sir Charles Lyell’s grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensibly vast have been the past periods of time, may at once close this volume. Not that it suffices to study the Principles of Geology, or to read special treatises by different observers on separate formations, and to mark how each author attempts to give an inadequate idea of the duration of each formation or even each stratum. A man must for years examine for himself great piles of superimposed strata, and watch the sea at work grinding down old rocks and making fresh sediment, before he can hope to comprehend anything of the lapse of time, the monuments of which we see around us.

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沿着由不很坚硬岩石所形成的海岸线漫步，注意看看陵削（degradation）过程是有好处的。在大多数情形里，达到海岸悬崖的海潮每天只有两次，且时间短暂，只有当波浪挟带着细沙砾石时才能侵蚀海岸岩崖；有良好的证据可以证明，清水对侵蚀岩石是没有什么效果的。最后，岩崖的基部终于被蚀空，大岩块倾落下来，碎块便固定在那里，然后一点一点地被侵蚀，直到体积缩小到能够被波浪翻滚的时候，才会很快地被磨碎成石子、砂或泥。但是我们常常看到后退的岩崖基部有圆形巨砾，密密覆盖着海产生物，表明它们很少被磨损，而且很少被翻滚！还有，如果我们沿着任何正在蒙受陵削作用的海岸岩崖行走几英里路，就会发现目前正在被陵削着的崖岸，不过只是短短的一段，或只是环绕海角，才断断续续存在着。地表和植被的外貌表明，基部被海水冲刷已经是许多年之前的事情了。

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It is good to wander along lines of sea-coast, when formed of moderately hard rocks, and mark the process of degradation. The tides in most cases reach the cliffs only for a short time twice a day, and the waves eat into them only when they are charged with sand or pebbles; for there is reason to believe that pure water can effect little or nothing in wearing away rock. At last the base of the cliff is undermined, huge fragments fall down, and these remaining fixed, have to be worn away, atom by atom, until reduced in size they can be rolled about by the waves, and then are more quickly ground into pebbles, sand, or mud. But how often do we see along the bases of retreating cliffs rounded boulders, all thickly clothed by marine productions, showing how little they are abraded and how seldom they are rolled about! Moreover, if we follow for a few miles any line of rocky cliff, which is undergoing degradation, we find that it is only here and there, along a short length or round a promontory, that the cliffs are at the present time suffering. The appearance of the surface and the vegetation show that elsewhere years have elapsed since the waters washed their base.

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我认为，认真研究我国海蚀现象的人，会对岩石海岸侵蚀的缓慢印象深刻。休·米勒和约旦山的优秀观察者史密斯先生在这方面的观察，十分令人瞩目。有鉴于此，任何人可以去观察厚度达数千英尺的砾岩层，虽然形成速度也许比其他沉积岩快一些，但由于是磨损的鹅卵石组成，每一块都带有时间的印记，很好地表明了岩层积累的缓慢。请记住赖尔深奥的评语，沉积层的厚度和广度是地壳其他地方所受陵削的结果和程度。许多地方的沉积层隐含着多么巨量的陵削啊！拉姆齐教授把英国不同部分的连续地质层的最大厚度告诉过我，根据是大多数场合里的实测，少数猜测，其结果如下：

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He who most closely studies the action of the sea on our shores, will, I believe, be most deeply impressed with the slowness with which rocky coasts are worn away. The observations on this head by Hugh Miller, and by that excellent observer Mr. Smith of Jordan Hill, are most impressive. With the mind thus impressed, let any one examine beds of conglomerate many thousand feet in thickness, which, though probably formed at a quicker rate than many other deposits, yet, from being formed of worn and rounded pebbles, each of which bears the stamp of time, are good to show how slowly the mass has been accumulated. Let him remember Lyell’s profound remark, that the thickness and extent of sedimentary formations are the result and measure of the degradation which the earth’s crust has elsewhere suffered. And what an amount of degradation is implied by the sedimentary deposits of many countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:—

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英尺

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Feet

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古生代层（火成岩层不在内） 57154

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Palaeozoic strata (not including igneous beds) 57154

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第二纪层 13190

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Secondary strata 13190

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第三纪层 2240

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Tertiary strata 2240

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——合计72584英尺：折合成英里差不多有十三又四分之三英里。有些地质层在英格兰只是一薄层，而在欧洲大陆上却厚达数千英尺。另外，每一个连续的地质层之间，按照大多数地质学者的意见，空白时期也极久长。所以英国沉积岩的高耸叠积层，只能对于所经过的堆积时间提供不确切的观念，想必消耗了何等漫长的时间啊！优秀观察者估计，密西西比大河的沉积速度是上万年只有600英尺。这种估计可能有错，可是考虑到海流传送极薄的沉积层跨越何等广阔的空间，任何一个地区的积累过程想必是极其缓慢的。

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—making altogether 72584 feet; that is, very nearly thirteen and three-quarters British miles. Some of these formations, which are represented in England by thin beds, are thousands of feet in thickness on the Continent. Moreover, between each successive formation, we have, in the opinion of most geologists, enormously long blank periods. So that the lofty pile of sedimentary rocks in Britain, gives but an inadequate idea of the time which has elapsed during their accumulation; yet what time this must have consumed! Good observers have estimated that sediment is deposited by the great Mississippi river at the rate of only 600 feet in a hundred thousand years. This estimate may be quite erroneous; yet, considering over what wide spaces very fine sediment is transported by the currents of the sea, the process of accumulation in any one area must be extremely slow.

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可是不考虑被剥蚀物质的积累速度，许多地方的地层剥蚀量也许能提供时间经过的最佳证据。记得看到火山岛被波浪冲蚀，四面削去成为高达一两千英尺的直立悬崖时，我曾深受剥蚀证据的触动；由于以前的液体状态，熔岩流凝成缓度斜面，一眼就可看出，坚硬的岩层一度在大洋里伸展得何等辽远。断层（faults）把这同类故事说得更明白——即那些巨大的裂隙，地层沿着断层在这一边隆起，或者在那一边陷下，高度或深度竟达数千英尺；自从地壳破裂以来，而今地表已经因海蚀作用而变得如此完全平坦，以致在外观上已经看不出这种巨大位错的任何痕迹。

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But the amount of denudation which the strata have in many places suffered, independently of the rate of accumulation of the degraded matter, probably offers the best evidence of the lapse of time. I remember having been much struck with the evidence of denudation, when viewing volcanic islands, which have been worn by the waves and pared all round into perpendicular cliffs of one or two thousand feet in height; for the gentle slope of the lava-streams, due to their formerly liquid state, showed at a glance how far the hard, rocky beds had once extended into the open ocean. The same story is still more plainly told by faults,—those great cracks along which the strata have been upheaved on one side, or thrown down on the other, to the height or depth of thousands of feet; for since the crust cracked, the surface of the land has been so completely planed down by the action of the sea, that no trace of these vast dislocations is externally visible.

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例如克拉文断层（Craven fault）延伸30多英里，沿着这一断层线，地层的垂直总变位自600到3000英尺不等。关于在盎格尔西（Anglesea）陷落达2300英尺的情形，拉姆齐教授曾发表过一篇报告；他告诉我说，他充分相信梅里奥尼斯郡（Merionethshire）有一个陷落竟达12000英尺。然而在这些情形里，地表上已没有任何东西可以表示这等巨大的运动了；裂隙两边的石堆已经夷为平地了。面对这种事实，使我得到一种印象，差不多就像去拿捏永恒这个概念一样无奈。

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The Craven fault, for instance, extends for upwards of 30 miles, and along this line the vertical displacement of the strata has varied from 600 to 3000 feet. Professor Ramsay has published an account of a downthrow in Anglesea of 2300 feet; and he informs me that he fully believes there is one in Merionethshire of 12000 feet; yet in these cases there is nothing on the surface to show such prodigious movements; the pile of rocks on the one or other side having been smoothly swept away. The consideration of these facts impresses my mind almost in the same manner as does the vain endeavour to grapple with the idea of eternity.

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我还想举一个著名的个案，威尔德地带的剥蚀。必须承认，该地带的剥蚀是小菜一碟，跟拉姆齐教授大作里的相关个案相比不值一提，那可是古生代地层的大剥蚀，部分地块的厚度达到一万英尺啊。可是，站在北唐斯山上，眺望南唐斯山，就是生动的一堂课。只要记住西边不远处，北南峭壁合拢了，就可以有把握地浮想联翩，只见威尔德地带从白垩地层后期开始的有限时期内覆盖着岩石大圆顶。南北唐斯山的距离大约是22英里，而各个地层的厚度平均为1100英尺，这是拉姆齐教授告诉我的。如果按照某些地质学家设想的那样，威尔德地带下面分布着更古老的岩石带，其侧翼的沉积岩覆盖会积累得比其他地方薄，那么上述估计就错误了。不过，这种疑点来源大概不会大大影响对于该地区极西点的估计。假如我们知道大海通常侵蚀任何给定高度的悬崖线的速度，就可以衡量剥蚀威尔德地带的时间要求。当然这是不可能做到的，但我们为了大致形成这方面的概念，可以假定大海侵蚀500英尺高悬崖的速度是每世纪一英寸。一开始这显得太慢，但这相当于一码高的悬崖在整个海岸线上侵蚀速度大约每二十二年一码。我怀疑任何岩石会以这个速度被侵蚀，哪怕柔软的白垩，除非是暴露无遗的海岸。当然高耸的悬崖陵削更快，因为有碎块掉下。另外，我不相信，一二十英里长的海岸线整个锯齿面同时陵削。必须记住，几乎所有的地层都含有坚硬的岩层结核，长期抵御磨损，形成基底防波堤。所以在普通情况下，我断言500英尺高的悬崖，整段剥蚀每世纪一英寸足够多了。这样，根据上述数据，威尔德地带的剥蚀必定需要306662400 年，也就是三亿来年。

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I am tempted to give one other case, the well-known one of the denudation of the Weald. Though it must be admitted that the denudation of the Weald has been a mere trifle, in comparison with that which has removed masses of our palaeozoic strata, in parts ten thousand feet in thickness, as shown in Professor Ramsay’s masterly memoir on this subject. Yet it is an admirable lesson to stand on the North Downs and to look at the distant South Downs; for, remembering that at no great distance to the west the northern and southern escarpments meet and close, one can safely picture to oneself the great dome of rocks which must have covered up the Weald within so limited a period as since the latter part of the Chalk formation. The distance from the northern to the southern Downs is about 22 miles, and the thickness of the several formations is on an average about 1100 feet, as I am informed by Professor Ramsay. But if, as some geologists suppose, a range of older rocks underlies the Weald, on the flanks of which the overlying sedimentary deposits might have accumulated in thinner masses than elsewhere, the above estimate would be erroneous; but this source of doubt probably would not greatly affect the estimate as applied to the western extremity of the district. If, then, we knew the rate at which the sea commonly wears away a line of cliff of any given height, we could measure the time requisite to have denuded the Weald. This, of course, cannot be done; but we may, in order to form some crude notion on the subject, assume that the sea would eat into cliffs 500 feet in height at the rate of one inch in a century. This will at first appear much too small an allowance; but it is the same as if we were to assume a cliff one yard in height to be eaten back along a whole line of coast at the rate of one yard in nearly every twenty-two years. I doubt whether any rock, even as soft as chalk, would yield at this rate excepting on the most exposed coasts; though no doubt the degradation of a lofty cliff would be more rapid from the breakage of the fallen fragments. On the other hand, I do not believe that any line of coast, ten or twenty miles in length, ever suffers degradation at the same time along its whole indented length; and we must remember that almost all strata contain harder layers or nodules, which from long resisting attrition form a breakwater at the base. Hence, under ordinary circumstances, I conclude that for a cliff 500 feet in height, a denudation of one inch per century for the whole length would be an ample allowance. At this rate, on the above data, the denudation of the Weald must have required 306662400 years; or say three hundred million years.

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清水对于微坡的威尔德地带抬高后的作用不可能很大，但会少许减少上述估算。另外，我们知道这个地区出现过水平面波动，作为陆地可能存在过千百万年，因此逃避了海侵：浸入海底同样长时间，则逃避了海岸波的作用。所以，从第二纪后期开始，过去的世纪很有可能比3亿年长得多。

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The action of fresh water on the gently inclined Wealden district, when upraised, could hardly have been great, but it would somewhat reduce the above estimate. On the other hand, during oscillations of level, which we know this area has undergone, the surface may have existed for millions of years as land, and thus have escaped the action of the sea: when deeply submerged for perhaps equally long periods, it would, likewise, have escaped the action of the coast-waves. So that in all probability a far longer period than 300 million years has elapsed since the latter part of the Secondary period.

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说这些话是因为我们很有必要得到一些岁月流逝的概念，管它多么不完善。每一年，全世界，陆地上和海水里居住着大批的生物类型。在漫长的年代里，想必有无数生物代代相传，头脑则无法加以把握！现在让我们看一看最丰富的地质博物馆，那里的陈列品是何等贫乏啊！

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I have made these few remarks because it is highly important for us to gain some notion, however imperfect, of the lapse of years. During each of these years, over the whole world, the land and the water has been peopled by hosts of living forms. What an infinite number of generations, which the mind cannot grasp, must have succeeded each other in the long roll of years! Now turn to our richest geological museums, and what a paltry display we behold!

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论古生物标本的贫乏。——大家都承认，古生物标本的搜集是极不完全的。永远不应忘记那位尊敬的古生物学者爱德华·福布斯的话，他说，大多数的化石物种都是根据单个的而且常常是破碎的标本，或者是根据某一个地点的少数标本而了解和命名的。地球表面只有一小部分曾做过地质学发掘，从欧洲每年的重要发现看来，可以说没有一处地方曾仔细发掘过。完全柔软的生物没有一种能够保存下来。落在海底的贝壳和骨骼，如果没有沉积物的掩盖，便会腐朽而消失。我认为我们始终采取了十分错误的观点，默认差不多整个海底都有沉积物正在进行堆积，并且其速度足够埋藏和保存化石的遗骸。海洋的极大部分都呈亮蓝色，这说明了水的纯净。记载下来的许多个案有，一个地质层经过长久间隔的时期以后，被另一后生的地质层整合遮盖起来，而下层在这间隔的时期中并未遭受任何磨损，这种情形，只有根据海底常常恒久不变的观点才可以得到解释。埋藏在沙子或砾层里的遗骸，遇到岩床上升的时候，一般会由于雨水的渗入而分解。我想，生长在海滩高潮与低潮之间的许多种类动物，难得保存下来。例如，藤壶亚科（Chthamalinlae，无柄蔓足类的亚科）的若干物种，在遍布全世界的海岸岩石上，数量非常之多。它们都是严格的海岸动物，除了在深海中生存的一个地中海物种在西西里被发现过化石以外，至今还没有在任何第三纪地质层里发现过任何其他物种；然而已经知道，藤壶属曾经生存于白垩纪。软体动物属石鳖（Chiton）的情况也差不多。

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On the poorness of our Palaeontological collections.—That our palaeontological collections are very imperfect, is admitted by every one. The remark of that admirable palaeontologist, the late Edward Forbes, should not be forgotten, namely, that numbers of our fossil species are known and named from single and often broken specimens, or from a few specimens collected on some one spot. Only a small portion of the surface of the earth has been geologically explored, and no part with sufficient care, as the important discoveries made every year in Europe prove. No organism wholly soft can be preserved. Shells and bones will decay and disappear when left on the bottom of the sea, where sediment is not accumulating. I believe we are continually taking a most erroneous view, when we tacitly admit to ourselves that sediment is being deposited over nearly the whole bed of the sea, at a rate sufficiently quick to embed and preserve fossil remains. Throughout an enormously large proportion of the ocean, the bright blue tint of the water bespeaks its purity. The many cases on record of a formation conformably covered, after an enormous interval of time, by another and later formation, without the underlying bed having suffered in the interval any wear and tear, seem explicable only on the view of the bottom of the sea not rarely lying for ages in an unaltered condition. The remains which do become embedded, if in sand or gravel, will when the beds are upraised generally be dissolved by the percolation of rain-water. I suspect that but few of the very many animals which live on the beach between high and low watermark are preserved. For instance, the several species of the Chthamalinae (a sub-family of sessile cirripedes) coat the rocks all over the world in infinite numbers: they are all strictly littoral, with the exception of a single Mediterranean species, which inhabits deep water and has been found fossil in Sicily, whereas not one other species has hitherto been found in any tertiary formation: yet it is now known that the genus Chthamalus existed during the chalk period. The molluscan genus Chiton offers a partially analogous case.

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毋庸赘言，第二纪和古生代的陆栖生物，我们所搜集的化石证据是极其支离破碎的。例如，直到最近，除了赖尔爵士在北美洲石炭纪地层中发现一个外，在这两个广阔时代中还没有发现过其他陆地贝壳。关于哺乳动物的遗骸，看一眼赖尔的《手册》附录的历史表，就可明白真相，比细读文字能更好地理解遗骸保存是何等的偶然和稀少。只要记住第三纪哺乳动物的骨骼大部分是在洞穴或湖沼的沉积物里发现的，且没有一个洞穴或湖成层是属于第二纪或古生代的地质层，稀少就不足为奇了。

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With respect to the terrestrial productions which lived during the Secondary and Palaeozoic periods, it is superfluous to state that our evidence from fossil remains is fragmentary in an extreme degree. For instance, not a land shell is known belonging to either of these vast periods, with one exception discovered by Sir C. Lyell in the carboniferous strata of North America. In regard to mammiferous remains, a single glance at the historical table published in the Supplement to Lyell’s Manual, will bring home the truth, how accidental and rare is their preservation, far better than pages of detail. Nor is their rarity surprising, when we remember how large a proportion of the bones of tertiary mammals have been discovered either in caves or in lacustrine deposits; and that not a cave or true lacustrine bed is known belonging to the age of our secondary or palaeozoic formations.

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但是，地质记录的不完全主要还是由于另外一个比上述任何原因更为重要的原因：地质层被广阔的间隔时期所隔开。当我们看到著作中地质层的表格，或者实地考察时，就很难不相信它们是密切连续的。但是，例如根据默奇森（R．Murchison）爵士关于俄罗斯的巨著，我们知道该国重叠的地质层之间有着何等广阔的间隙；在北美洲以及世界的许多其他地方也是如此。如果最熟练的地质学者只把注意力局限在这等广大地域，那么他决不会想象到，在他的本国还是空白不毛的时代里，巨大沉积物已在世界其他地方堆积起来了，而且其中含有新而特别的生物类型。同时，如果在各个分离的地域内，对于连续地质层之间所经过的时间长度不能形成任何概念，那么我们可以推论在任何地方都不能确立这种概念。连续地质层的矿物构成屡屡发生巨变，一般意味着周围地域有地理上的巨大变化，因此便产生了沉积物，这与各个地质层之间曾有过极久的间隔时期的观点是相符合的。

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But the imperfection in the geological record mainly results from another and more important cause than any of the foregoing; namely, from the several formations being separated from each other by wide intervals of time. When we see the formations tabulated in written works, or when we follow them in nature, it is difficult to avoid believing that they are closely consecutive. But we know, for instance, from Sir R. Murchison’s great work on Russia, what wide gaps there are in that country between the superimposed formations; so it is in North America, and in many other parts of the world. The most skilful geologist, if his attention had been exclusively confined to these large territories, would never have suspected that during the periods which were blank and barren in his own country, great piles of sediment, charged with new and peculiar forms of life, had elsewhere been accumulated. And if in each separate territory, hardly any idea can be formed of the length of time which has elapsed between the consecutive formations, we may infer that this could nowhere be ascertained. The frequent and great changes in the mineralogical composition of consecutive formations, generally implying great changes in the geography of the surrounding lands, whence the sediment has been derived, accords with the belief of vast intervals of time having elapsed between each formation.

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我想，我们能理解为什么各区域的地质层几乎一律是间断的；就是说不是彼此紧挨着。最打动我的是，当我调查最近期间升高几百英尺的南美洲千百英里海岸时，竟没有任何近代的沉积物有足够的广度，可以持续哪怕是一个短的地质时代而不被磨灭。全部西海岸都有特别海产动物栖息着，可是那里的第三纪层非常不发达，大概没有各种连续而特别的海产动物的记录会保存到久远的年代。只要稍微一想，便能解释为什么沿着南美洲西边升起的海岸，不能到处发现含有近期，即第三纪的遗骸的大范围地质层，虽然在悠久的年代里沉积物的供给一定是丰富的，有海岸岩石的大量陵削和注入海洋里的泥河。无疑应当这样解释，即当海岸和近海岸沉积物一旦被缓慢而逐渐升高的陆地带到海岸波浪研磨作用的范围之内时，便会不断地被侵蚀掉。

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But we can, I think, see why the geological formations of each region are almost invariably intermittent; that is, have not followed each other in close sequence. Scarcely any fact struck me more when examining many hundred miles of the South American coasts, which have been upraised several hundred feet within the recent period, than the absence of any recent deposits sufficiently extensive to last for even a short geological period. Along the whole west coast, which is inhabited by a peculiar marine fauna, tertiary beds are so scantily developed, that no record of several successive and peculiar marine faunas will probably be preserved to a distant age. A little reflection will explain why along the rising coast of the western side of South America, no extensive formations with recent or tertiary remains can anywhere be found, though the supply of sediment must for ages have been great, from the enormous degradation of the coast-rocks and from muddy streams entering the sea. The explanation, no doubt, is, that the littoral and sub-littoral deposits are continually worn away, as soon as they are brought up by the slow and gradual rising of the land within the grinding action of the coast-waves.

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我想，我们可以有把握地断言，沉积物必须堆积成极厚的、极结实的、极大的巨块，才能在最初升高和水平面波动的期间，抵御波浪的不断作用以及其后的大气陵削作用。这样又厚又大的沉积物堆积可由两种途径形成：一是在深海底进行堆积，按照E．福布斯的研究成果，我们断言，深海底极少有动物栖息，所以当大块沉积物上升之后，对于当时生存的生物类型所提供的记录是很不完全的；另一是在浅海底进行堆积，如果浅海底不断徐徐沉陷，沉积物就可以堆积到任何的厚度和广度。在后一种情形里，只要海底沉陷的速度与沉积物的供给差不多平衡，海就会一直是浅的，而且有利于生物生存，这样，一个富含化石的地质层便形成，而且在上升变为陆地时，厚度也足以抵抗大量的陵削。

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We may, I think, safely conclude that sediment must be accumulated in extremely thick, solid, or extensive masses, in order to withstand the incessant action of the waves, when first upraised and during subsequent oscillations of level. Such thick and extensive accumulations of sediment may be formed in two ways; either, in profound depths of the sea, in which case, judging from the researches of E. Forbes, we may conclude that the bottom will be inhabited by extremely few animals, and the mass when upraised will give a most imperfect record of the forms of life which then existed; or, sediment may be accumulated to any thickness and extent over a shallow bottom, if it continue slowly to subside. In this latter case, as long as the rate of subsidence and supply of sediment nearly balance each other, the sea will remain shallow and favourable for life, and thus a fossiliferous formation thick enough, when upraised, to resist any amount of degradation, may be formed.

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我相信，所有的古代地质层，凡是富含化石的，都是这样在沉陷期间形成的。自从1845年我发表了关于这个问题的观点之后，就注意着地质学的进展，使我感到惊奇的是，当作者们讨论到这种或那种巨大地质层时，纷纷得出结论，是在海底沉陷期间堆积起来的。我可以补充说，南美洲西岸的唯一古代第三纪地质层肯定就是在水平面向下沉陷期间堆积起来的，并且由此达到了相当的厚度；这一地质层虽然厚度巨大，足以抵抗它曾经蒙受过的那种陵削作用，但今后将很难持续到久远的地质时代里去。

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I am convinced that all our ancient formations, which are rich in fossils, have thus been formed during subsidence. Since publishing my views on this subject in 1845, I have watched the progress of Geology, and have been surprised to note how author after author, in treating of this or that great formation, has come to the conclusion that it was accumulated during subsidence. I may add, that the only ancient tertiary formation on the west coast of South America, which has been bulky enough to resist such degradation as it has as yet suffered, but which will hardly last to a distant geological age, was certainly deposited during a downward oscillation of level, and thus gained considerable thickness.

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所有地质学事实都明白地告诉我们，每个地域都曾经过许多缓慢的水平面波动，而且波动的影响范围显然是很大的。结果，富含化石且广度和厚度足以抵抗其后陵削作用的地质层，在沉陷期间，是在广大的范围内形成的，但只限于沉积物的供给足以保持海水的浅度并且足以在遗骸未腐化以前把它们埋藏和保存起来的地方。相反，在海底保持静止的期间，沉积物就不能在最适于生物生存的浅海部分厚积。在上升的交替期间，这种情形就更少发生；确切些说，那时堆积起来的海床，由于升起和进入海岸作用的界限之内，一般都毁坏了。

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All geological facts tell us plainly that each area has undergone numerous slow oscillations of level, and apparently these oscillations have affected wide spaces. Consequently formations rich in fossils and sufficiently thick and extensive to resist subsequent degradation, may have been formed over wide spaces during periods of subsidence, but only where the supply of sediment was sufficient to keep the sea shallow and to embed and preserve the remains before they had time to decay. On the other hand, as long as the bed of the sea remained stationary, thick deposits could not have been accumulated in the shallow parts, which are the most favourable to life. Still less could this have happened during the alternate periods of elevation; or, to speak more accurately, the beds which were then accumulated will have been destroyed by being upraised and brought within the limits of the coast-action.

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于是，地质记录势必要断断续续的了。我对这种观点的正确性有把握，它们严格遵循赖尔爵士谆谆教导的一般原理，而且福布斯独立取得了类似的结论。

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Thus the geological record will almost necessarily be rendered intermittent. I feel much confidence in the truth of these views, for they are in strict accordance with the general principles inculcated by Sir C. Lyell; and E. Forbes independently arrived at a similar conclusion.

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这里还有一句话值得稍加注意。在抬升期间，陆地面积以及连接的浅海滩面积将会增大，而且常常形成新的生物活动场所；——前面已经说过，所有环境条件对于新变种和新种的形成是极有利的；但是这期间地质记录上一般是空白的。另一方面，在沉陷期间，生物分布的面积和生物数目将会减少（最初分裂为群岛的大陆海岸除外），结果，沉陷期间虽然会发生生物的大量灭绝，但少数新变种或新物种却会形成；而且也是在这一沉陷期间，富含化石的沉积物将被堆积起来。几乎可以说，自然防止了过渡或者连接类型的频繁发现。

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One remark is here worth a passing notice. During periods of elevation the area of the land and of the adjoining shoal parts of the sea will be increased, and new stations will often be formed;—all circumstances most favourable, as previously explained, for the formation of new varieties and species; but during such periods there will generally be a blank in the geological record. On the other hand, during subsidence, the inhabited area and number of inhabitants will decrease (excepting the productions on the shores of a continent when first broken up into an archipelago), and consequently during subsidence, though there will be much extinction, fewer new varieties or species will be formed; and it is during these very periods of subsidence, that our great deposits rich in fossils have been accumulated. Nature may almost be said to have guarded against the frequent discovery of her transitional or linking forms.

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从上述的理由看，无疑地质记载从整体来看是极不完全的。但是，如果把注意力只局限在任一地质层上，就更难理解为什么始终生活在其中的亲缘物种之间，没有发现密切级进的诸变种。同一个物种在同一地质层的上部和下部呈现清晰的变种，这些情形有记载，但很稀少，可以忽略。虽然各地质层的沉积无可争论地需要极久的年代，还可以举出若干理由来说明，为什么都不包含一个级进的环节系列，介于当时生活的物种之间；但我对于下述理由，还不敢声称给予了相应的重视。

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From the foregoing considerations it cannot be doubted that the geological record, viewed as a whole, is extremely imperfect; but if we confine our attention to any one formation, it becomes more difficult to understand, why we do not therein find closely graduated varieties between the allied species which lived at its commencement and at its close. Some cases are on record of the same species presenting distinct varieties in the upper and lower parts of the same formation, but, as they are rare, they may be here passed over. Although each formation has indisputably required a vast number of years for its deposition, I can see several reasons why each should not include a graduated series of links between the species which then lived; but I can by no means pretend to assign due proportional weight to the following considerations.

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虽然各地质层可以表示一个极久时间过程，但比起一个物种变为另一个物种所需要的时间，也许还显得短些。古生物学者勃龙（Bronn）和伍德沃德（Woodward）曾经断言，各地质层的平均存续期间比物种类型的平均存续期间长两三倍。我知道他们的意见很值得尊重，但是，在我看来，有不可克服的许多困难阻碍着我们在这方面下任何恰当的结论。当我们看到一个物种最初在任何地质层的中央部分出现，就去推论它以前不曾在他处存在过的话，那是极其轻率的。还有，当我们看到一个物种在一个沉积层最上面部分形成以前就消灭，就去假定它在那时已经全部灭绝，也是同等轻率的。我们忘记了欧洲的面积和全世界比起来是何等的小，而全欧洲同一地质层的几个阶段也不是完全确切相关的。

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Although each formation may mark a very long lapse of years, each perhaps is short compared with the period requisite to change one species into another. I am aware that two palaeontologists, whose opinions are worthy of much deference, namely Bronn and Woodward, have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms. But insuperable difficulties, as it seems to me, prevent us coming to any just conclusion on this head. When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again when we find a species disappearing before the uppermost layers have been deposited, it would be equally rash to suppose that it then became wholly extinct. We forget how small the area of Europe is compared with the rest of the world; nor have the several stages of the same formation throughout Europe been correlated with perfect accuracy.

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我们可以稳妥地推论，一切种类的海产动物由于气候等的变化，都曾有大规模的迁徙；当我们看到一个物种最初在任何地质层中出现时，可能是那时刚刚迁移到这个区域中去的。例如，众所周知，若干物种在北美洲古生代层出现的时间比欧洲同样地层为早，显然从美洲的海迁移到欧洲的海是需要时间的。在考察世界各地最近沉积物的时候，到处都可看见少数至今依然生存的某些物种在沉积物中虽很普通，但在周围密接的海中则已灭绝；相反，某些物种在周围邻近海中现在虽很繁盛，但在这一沉积物中却是绝无仅有。考察一下欧洲冰期（只是一个全地质时期的一部分）生物的确认迁徙量，期间的海陆沧桑，气候的极端变化，以及时间的悠久经过，都是同一个冰期内发生的，这不失为很好的一课。然而在世界的任何部分，含有化石遗骸的沉积层，是否曾经在整个这一冰期于同一区域内连续进行堆积，是存疑的。例如，密西西比河口附近，在海产动物能够繁生的深度范围以内，沉积物不可能在整个冰期内堆积起来；我们知道，此期间美洲的其他地方曾经发生过巨大的地理变化。像在密西西比河口附近浅水中于冰期的某一分期内沉积起来的这等地层，在上升的时候，生物的遗骸由于物种迁徙和地理变化，大概会最初出现和消失在不同的水平面中。在遥远的将来，如果有一位地质学者调查这等地层，大概要下结论，那里埋藏的化石生物的平均持续过程比冰期的期间为短，而不说实际上远比冰期为长，这就是说，它们从冰期以前一直延续到今日。

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With marine animals of all kinds, we may safely infer a large amount of migration during climatal and other changes; and when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area. It is well known, for instance, that several species appeared somewhat earlier in the palaeozoic beds of North America than in those of Europe; time having apparently been required for their migration from the American to the European seas. In examining the latest deposits of various quarters of the world, it has everywhere been noted, that some few still existing species are common in the deposit, but have become extinct in the immediately surrounding sea; or, conversely, that some are now abundant in the neighbouring sea, but are rare or absent in this particular deposit. It is an excellent lesson to reflect on the ascertained amount of migration of the inhabitants of Europe during the glacial period, which forms only a part of one whole geological period; and likewise to reflect on the great changes of level, on the inordinately great change of climate, on the prodigious lapse of time, all included within this same glacial period. Yet it may be doubted whether in any quarter of the world, sedimentary deposits, including fossil remains, have gone on accumulating within the same area during the whole of this period. It is not, for instance, probable that sediment was deposited during the whole of the glacial period near the mouth of the Mississippi, within that limit of depth at which marine animals can flourish; for we know what vast geographical changes occurred in other parts of America during this space of time. When such beds as were deposited in shallow water near the mouth of the Mississippi during some part of the glacial period shall have been upraised, organic remains will probably first appear and disappear at different levels, owing to the migration of species and to geographical changes. And in the distant future, a geologist examining these beds, might be tempted to conclude that the average duration of life of the embedded fossils had been less than that of the glacial period, instead of having been really far greater, that is extending from before the glacial epoch to the present day.

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为了在同一个地质层的上、下部得到介于两个类型之间的完全级进系列，沉积物必须在长久期间内连续进行堆积，以便来得及进行缓慢的变异过程；因此，这堆积物一定是极厚的，并且进行着变异的物种一定是在整个期间生活在同一区域中。但是我们知道，含有化石的厚地质层，只有在沉陷期间才能堆积起来；并且沉积物的供给必须抵消沉陷量，使海水深度保持平稳，才可以使同种物种在同一地方生活。但是，这种沉陷运动有使沉积物来源地沉没在水中的倾向，所以沉陷运动持续时，便会减少沉积物供给。事实上，沉积物的供给和沉陷量之间完全接近平衡，大概是一种罕见的偶然事情；因为不止一个古生物学者观察到在极厚的沉积物中，除了它们的上下限附近，通常是没有生物遗骸的。

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In order to get a perfect gradation between two forms in the upper and lower parts of the same formation, the deposit must have gone on accumulating for a very long period, in order to have given sufficient time for the slow process of variation; hence the deposit will generally have to be a very thick one; and the species undergoing modification will have had to live on the same area throughout this whole time. But we have seen that a thick fossiliferous formation can only be accumulated during a period of subsidence; and to keep the depth approximately the same, which is necessary in order to enable the same species to live on the same space, the supply of sediment must nearly have counterbalanced the amount of subsidence. But this same movement of subsidence will often tend to sink the area whence the sediment is derived, and thus diminish the supply whilst the downward movement continues. In fact, this nearly exact balancing between the supply of sediment and the amount of subsidence is probably a rare contingency; for it has been observed by more than one palaeontologist, that very thick deposits are usually barren of organic remains, except near their upper or lower limits.

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各个单独的地质层似乎和任何地方的整个地质层相似，堆积一般也是间断的。正如常常看到的那样，一个地质层由极其不同的矿物层构成时，我们可以合理地去设想沉积过程曾经备受打扰，而洋流变化、不同沉积物的供应一般是旷日持久的地理变化造成的。哪怕极其细密地对一个地质层进行考察，也无法知道其沉积所耗费的时间长度。许多事例阐明，厚仅数英尺的岩层，却代表着其他地方厚达数千英尺、因而堆积需要莫大时间的地层，但不知情的人们会怀疑这样薄的地质层会代表长久时间的过程。还有，地质层的下层升高后，被剥蚀，再沉没，继而被同一地质层的上层所覆盖，这方面例子也很多。这表明它的堆积期间有何等广阔的间隔时期，容易被人忽视。更有甚者，巨大的硅化木依然像当年生长时那样直立着，这明显证明了沉积过程有许多长的间隔期间以及水平面的变化，如果没有树木碰巧保存下来，大概不会想到这一点的。例如，赖尔和道森先生曾在加拿大新斯科舍省（Nova Scotia）发现了1400英尺厚的石炭纪层，含有古代树根的层次，彼此相叠，不少于68层不同的水平面。因此，如果一个地质层的下、中、上部都出现了同一个物种，可能是这个物种没有在沉积的全部期间生活在同一地点，而是在同一个地质时代内曾经几度绝迹和重现。所以，如果这个物种在任何一个地质年代内发生了显著的变异，则地质层的截面也许不会含有我的理论上一定存在的全部微细的中间级进，而只是含有突然变化的类型，虽然也许是轻微的。

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It would seem that each separate formation, like the whole pile of formations in any country, has generally been intermittent in its accumulation. When we see, as is so often the case, a formation composed of beds of different mineralogical composition, we may reasonably suspect that the process of deposition has been much interrupted, as a change in the currents of the sea and a supply of sediment of a different nature will generally have been due to geographical changes requiring much time. Nor will the closest inspection of a formation give any idea of the time which its deposition has consumed. Many instances could be given of beds only a few feet in thickness, representing formations, elsewhere thousands of feet in thickness, and which must have required an enormous period for their accumulation; yet no one ignorant of this fact would have suspected the vast lapse of time represented by the thinner formation. Many cases could be given of the lower beds of a formation having been upraised, denuded, submerged, and then re-covered by the upper beds of the same formation,—facts, showing what wide, yet easily overlooked, intervals have occurred in its accumulation. In other cases we have the plainest evidence in great fossilised trees, still standing upright as they grew, of many long intervals of time and changes of level during the process of deposition, which would never even have been suspected, had not the trees chanced to have been preserved: thus, Messrs. Lyell and Dawson found carboniferous beds 1400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the other, at no less than sixty-eight different levels. Hence, when the same species occur at the bottom, middle, and top of a formation, the probability is that they have not lived on the same spot during the whole period of deposition, but have disappeared and reappeared, perhaps many times, during the same geological period. So that if such species were to undergo a considerable amount of modification during any one geological period, a section would not probably include all the fine intermediate gradations which must on my theory have existed between them, but abrupt, though perhaps very slight, changes of form.

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最重要的是要记住，学者们没有金科玉律来区别物种和变种；他们承认各物种都有细小的变异性，但当他们遇到任何两个类型之间有稍微大一些的差异量，除非有密切的中间级进把它们连接起来，否则就要把两个类型都列为物种。按照刚才所讲的理由，我们不可能希望在任何一个地质的截面中都看到这种连接。假定B和C是两个物种，并且在下面的地层中发现第三个A；哪怕A严格地介于B和C之间，除非它能同时被一些中间变种与上述任何一个类型或两个类型极密切连接起来，否则就会干脆被排列为第三个物种。不要忘记，如同前面所解释的，A也许是B和C的实际原始祖先，但在各方面构造并不一定严格地都介于两者之间。所以，我们可能从同一个地质层的下、上层中得到亲种和它的若干变异后代，不过如果没有同时得到无数的过渡级进，就辨识不出其血统关系，因而就不得不把它们排列为不同的物种。

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It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by close intermediate gradations. And this from the reasons just assigned we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an underlying bed; even if A were strictly intermediate between B and C, it would simply be ranked as a third and distinct species, unless at the same time it could be most closely connected with either one or both forms by intermediate varieties. Nor should it be forgotten, as before explained, that A might be the actual progenitor of B and C, and yet might not at all necessarily be strictly intermediate between them in all points of structure. So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of a formation, and unless we obtained numerous transitional gradations, we should not recognise their relationship, and should consequently be compelled to rank them all as distinct species.

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众所周知，许多古生物学者是根据何等微小的差异来区别物种的。如果标本得自同一个地质层的不同层次，他们就更毫不犹豫了。某些有经验的贝类学者，现在已把多比内（D’Orbigny）等学者所定的许多极完全的物种降为变种了；根据这种观点，我们确能看到按照我的理论所应当看到的那类变化证据。而且，如果我们观察一下稍广阔的间隔时期，就是说观察一下同一个巨大地质层中的不同而连续的层次，就会看到埋藏的化石，虽然普遍被列为不同的物种，但彼此之间的关系比起相隔更远的地质层中的物种，要密切得多；但是这个问题只能留待下章再加讨论。

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It is notorious on what excessively slight differences many palaeontologists have founded their species; and they do this the more readily if the specimens come from different sub-stages of the same formation. Some experienced conchologists are now sinking many of the very fine species of D’Orbigny and others into the rank of varieties; and on this view we do find the kind of evidence of change which on my theory we ought to find. Moreover, if we look to rather wider intervals, namely, to distinct but consecutive stages of the same great formation, we find that the embedded fossils, though almost universally ranked as specifically different, yet are far more closely allied to each other than are the species found in more widely separated formations; but to this subject I shall have to return in the following chapter.

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还有一个理由值得注意：关于繁殖快而移动不大的动植物，像前面已经看到的那样，有理由来推测，它们的变种最初一般是地方性的；这种地方性的变种，非到相当程度地改变完善了，不会广为分布去淘汰它们的亲类型的。按照这种观点，任何地方的一个地质层中要想发现任何两个类型之间的一切早期过渡阶段，机会是很小的，因为连续的变化被假定是地方性的，局限于某一地点。大多数海产动物的分布范围都是广大的；并且我们看到，植物里分布范围最广的，最常呈现变种；所以，关于贝类等海产动物，那些具有最广大分布范围的，远远超过已知的欧洲地质层界限以外的，最常先产生地方变种，终于产生新物种；因此，我们在任何一个地质层中追踪过渡诸阶段的机会又大大减少了。

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One other consideration is worth notice: with animals and plants that can propagate rapidly and are not highly locomotive, there is reason to suspect, as we have formerly seen, that their varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-forms until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two forms, is small, for the successive changes are supposed to have been local or confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so that with shells and other marine animals, it is probably those which have had the widest range, far exceeding the limits of the known geological formations of Europe, which have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one geological formation.

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不应忘记，今天有完美的标本供观察，却很少能用中间变种把两个类型连接起来，从而证明它们同种，除非从许多地方采集到许多标本。而在化石物种方面，学者极少能够做到多方采集。我们只要问问，例如，地质学者在某一未来时代能否证明牛羊、马狗各品种是从一个或几个原始祖先传下来的，又如，栖息在北美洲海岸的某些海贝实际上是变种呢，还是所谓的不同物种呢？（某些学者列为物种，不同于欧洲代表种，而另一些学者仅仅列为变种。）这样一问，我们恐怕就能最好地了解用大量微细的中间化石环节来连接物种是不可能的。未来的地质学者只有发现了化石状态的大量中间级进之后，才能证明这一点，而依我看这种成功是画饼充饥。

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It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate varieties and thus proved to be the same species, until many specimens have been collected from many places; and in the case of fossil species this could rarely be effected by palaeontologists. We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous, fine, intermediate, fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove, that our different breeds of cattle, sheep, horses, and dogs have descended from a single stock or from several aboriginal stocks; or, again, whether certain sea-shells inhabiting the shores of North America, which are ranked by some conchologists as distinct species from their European representatives, and by other conchologists as only varieties, are really varieties or are, as it is called, specifically distinct. This could be effected only by the future geologist discovering in a fossil state numerous intermediate gradations; and such success seems to me improbable in the highest degree.

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地质学研究虽然替现存和灭绝的属里增加了大量物种，并且使少数物种群之间的间隔比原来缩小，却并没有通过大量微细的中间变种把物种连接起来，从而打破物种之间的区别。由于这一点没有做到，也许成为反对我的观点的一个最重大最明显的异议。值得用一个想象的例证把上述诸原因总结一下。马来群岛的面积大约相当于从北角（North Cape）到地中海以及从英国到俄罗斯的欧洲面积；所以，除去美国的地质层之外，面积与多少精确调查过的全部地质层不相上下。我完全同意戈德温-奥斯汀（Godwin-Austen）先生的意见，马来群岛的现状（大量大岛屿被广阔的浅海所隔开），大概可以代表欧洲以前的状况，大多数地质层正在进行堆积。马来群岛是全球生物方面最丰富的区域之一，然而，如果把所有曾经生活在那里的物种都搜集起来，就会看出它们所代表的世界博物史是何等不完全！

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Geological research, though it has added numerous species to existing and extinct genera, and has made the intervals between some few groups less wide than they otherwise would have been, yet has done scarcely anything in breaking down the distinction between species, by connecting them together by numerous, fine, intermediate varieties; and this not having been effected, is probably the gravest and most obvious of all the many objections which may be urged against my views. Hence it will be worth while to sum up the foregoing remarks, under an imaginary illustration. The Malay Archipelago is of about the size of Europe from the North Cape to the Mediterranean, and from Britain to Russia; and therefore equals all the geological formations which have been examined with any accuracy, excepting those of the United States of America. I fully agree with Mr. Godwin-Austen, that the present condition of the Malay Archipelago, with its numerous large islands separated by wide and shallow seas, probably represents the former state of Europe, when most of our formations were accumulating. The Malay Archipelago is one of the richest regions of the whole world in organic beings; yet if all the species were to be collected which have ever lived there, how imperfectly would they represent the natural history of the world!

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但是我们有充分理由认为，马来群岛的陆栖生物在我们假定堆积在那里的地质层中，保存得极不完全。我想，严格的海岸动物，或生活在海底裸露岩石上的动物，被埋藏的不会很多；而且那些被埋藏在砾石和沙中的生物也不会保存到久远的时代。在海底没有沉积物堆积的地方，或者在堆积的速率不足以保护生物体免于腐败的地方，遗骸便不能保存下来。

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But we have every reason to believe that the terrestrial productions of the archipelago would be preserved in an excessively imperfect manner in the formations which we suppose to be there accumulating. I suspect that not many of the strictly littoral animals, or of those which lived on naked submarine rocks, would be embedded; and those embedded in gravel or sand, would not endure to a distant epoch. Wherever sediment did not accumulate on the bed of the sea, or where it did not accumulate at a sufficient rate to protect organic bodies from decay, no remains could be preserved.

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在马来群岛，我想含化石地质层只能于沉陷期间形成，使其厚度足以延续到一个世代，在未来时代中延续的距离，不亚于过去第二纪层那样悠久。这等沉陷期间彼此要被巨大的间隔时期所分开，在这期间，地面要么保持静止要么继续上升；上升时，每个含化石地质层，会被不断的海岸作用随堆积随毁坏，就如我们现今在南美洲海岸所见到的那样。在沉陷期间，生物灭绝也许极多；在上升期间，大概会出现极多的生物变异，可是这个时候的地质记录极不完全。

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In our archipelago, I believe that fossiliferous formations could be formed of sufficient thickness to last to an age, as distant in futurity as the secondary formations lie in the past, only during periods of subsidence. These periods of subsidence would be separated from each other by enormous intervals, during which the area would be either stationary or rising; whilst rising, each fossiliferous formation would be destroyed, almost as soon as accumulated, by the incessant coast-action, as we now see on the shores of South America. During the periods of subsidence there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be least perfect.

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群岛全部或一部分沉陷以及与此同时发生的沉积物堆积的任何漫长时间，是否会超过同一物种类型的平均持续期间，是可疑的；这等偶然的事情对于任何两个以上物种之间的一切过渡级进的保存是不可缺少的。如果这等级进没有全部保存下来，过渡的变种看上去只能像是许多不同的物种。各个沉陷的漫长期间还可能被水平面的波动所打断，同时在这样长久的期间内，轻微的气候变化也可能发生；在这等情形下，群岛的生物就要迁移，因而在任何一个地质层里就不能保存有关它们变异的紧密连接的记录。

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It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would exceed the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not fully preserved, transitional varieties would merely appear as so many distinct species. It is, also, probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would have to migrate, and no closely consecutive record of their modifications could be preserved in any one formation.

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群岛的多数海产生物，现在已超越了它的界限而分布到数千英里以外；以此类推，可以使我相信，主要是这些广为分布的物种，最常产生新变种。这等变种最初是地方性的，局限于一个地方，但当它们得到了任何明确的优势，或者进一步变异和改进时，就会慢慢地散布开去，并且把亲缘类型淘汰掉。当这等变种重返故乡时，因已不同于先前的状态，虽然其程度也许是极其轻微的，却是一刀切的，所以按照许多古生物学者所遵循的原理，它们大概会被列为不同的新物种。

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Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy leads me to believe that it would be chiefly these far-ranging species which would oftenest produce new varieties; and the varieties would at first generally be local or confined to one place, but if possessed of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former state, in a nearly uniform, though perhaps extremely slight degree, they would, according to the principles followed by many palaeontologists, be ranked as new and distinct species.

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如果这等说法有某种程度的正确性，我们就没有权利去期望在地质层中找到这等无限数目的、差别微小的过渡类型。按照我的理论，这些类型曾经把一切同群的过去物种和现在物种连接在一条长而分枝的生物环节中。我们只应寻找少数的环节，它们的彼此关系有的远些，有的近些；而这等环节，就算是极密切的，如果见于同一地质层的不同层次，也会被许多古生物学者列为不同的物种。我不讳言，如果不是在每一地质层的初期及末期生存的物种之间缺少无数过渡的环节，而对我的理论构成如此严重威胁的话，我将不会想到在保存得最好的地质断面中，生物突变的记录还是如此贫乏。

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If then, there be some degree of truth in these remarks, we have no right to expect to find in our geological formations, an infinite number of those fine transitional forms, which on my theory assuredly have connected all the past and present species of the same group into one long and branching chain of life. We ought only to look for a few links, some more closely, some more distantly related to each other; and these links, let them be ever so close, if found in different stages of the same formation, would, by most palaeontologists, be ranked as distinct species. But I do not pretend that I should ever have suspected how poor a record of the mutations of life, the best preserved geological section presented, had not the difficulty of our not discovering innumerable transitional links between the species which appeared at the commencement and close of each formation, pressed so hardly on my theory.

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全群近似物种的突然出现。——物种全群在某些地质层中突然出现的事情，曾被某些古生物学者——如阿加西斯、匹克推特，特别是塞奇威克（Sedgwick）教授——看作是反对物种能够变迁这一观点的致命异议。如果同属或同科的大量物种真的一下子降生了，那么对于通过自然选择而缓慢变异的遗传学说，的确是致命的。因为依据自然选择，所有从某一个祖先传下来的一群类型的发展，一定是极其缓慢的过程；并且这些祖先一定在变异后代出现以前就已经生存很久了。但是，我们始终把地质记录的完全性估价得过高，并且由于某属或某科未曾见于某一阶段下面，就错误地推论在那个阶段以前没有存在过。我们常常忘记，整个世界与仔细调查过的地质层的面积比较起来，是何等巨大；我们还会忘记物种群在侵入欧洲和美国的古代群岛以前，也许在他处已经存在了很久，而且慢慢地繁衍着。我们也没有适当地考虑到在我们的连续地质层之间所经过的间隔时间——这一时间有时候大概要比各个地质层堆积起来所需要的时间更长久。这些间隔会给予充分的时间使物种从某一个、若干个亲类型繁衍下来；而这种物种在以后生成的地质层中好像突然创造出来似的出现了。

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On the sudden appearance of whole groups of Allied Species.—The abrupt manner in which whole groups of species suddenly appear in certain formations, has been urged by several palaeontologists, for instance, by Agassiz, Pictet, and by none more forcibly than by Professor Sedgwick, as a fatal objection to the belief in the transmutation of species. If numerous species, belonging to the same genera or families, have really started into life all at once, the fact would be fatal to the theory of descent with slow modification through natural selection. For the development of a group of forms, all of which have descended from some one progenitor, must have been an extremely slow process; and the progenitors must have lived long ages before their modified descendants. But we continually over-rate the perfection of the geological record, and falsely infer, because certain genera or families have not been found beneath a certain stage, that they did not exist before that stage. We continually forget how large the world is, compared with the area over which our geological formations have been carefully examined; we forget that groups of species may elsewhere have long existed and have slowly multiplied before they invaded the ancient archipelagoes of Europe and of the United States. We do not make due allowance for the enormous intervals of time, which have probably elapsed between our consecutive formations,—longer perhaps in some cases than the time required for the accumulation of each formation. These intervals will have given time for the multiplication of species from some one or some few parent-forms; and in the succeeding formation such species will appear as if suddenly created.

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这里我要把以前说过的话再说一遍，即，一种生物对于某种特别的新生活方式的适应，例如空中飞翔，大概是需要长久连续的年代；但是，如果这种适应一旦成功，并且少数物种就此比别的物种获得了巨大的优势，那么只要较短的时间内，就能产生出许多分歧的类型来，从而迅速地、广泛地散布于全世界。

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I may here recall a remark formerly made, namely that it might require a long succession of ages to adapt an organism to some new and peculiar line of life, for instance to fly through the air; but that when this had been effected, and a few species had thus acquired a great advantage over other organisms, a comparatively short time would be necessary to produce many divergent forms, which would be able to spread rapidly and widely throughout the world.

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我现在举几个例子来证明前面的话，表明我们何等容易犯错误，去假定全群物种曾经突然产生。我可以再提一件大家熟知的事实，几年前发表的一些地质学论文中，都说哺乳动物纲是在第三纪开头才突然出现的。而现在已知的富含化石哺乳动物的堆积物之一，是属于第二纪层的中期的；并且在这个大纪刚刚开头的新红砂岩中发现了一头真的哺乳动物。居维叶一贯主张，任何第三纪层没有猴子出现过；但是，目前在印度、南美洲和欧洲甚至于更古的第三纪始新统中发现了猴的灭绝种。不过，最最触目惊心的个案是鲸科。这种海生动物骨骼巨大，全世界分布，所以第二纪地层没有发现一根鲸骨的事实，似乎充分证实了这个大目突然产生的观点，时间是第二纪末期与第三纪早期地层。可是，我们现在可以在1858年发表的赖尔《手册》增刊中看到鲸在上层海绿石砂中存在的明证，年代略早于第二纪末年。

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I will now give a few examples to illustrate these remarks; and to show how liable we are to error in supposing that whole groups of species have suddenly been produced. I may recall the well-known fact that in geological treatises, published not many years ago, the great class of mammals was always spoken of as having abruptly come in at the commencement of the tertiary series. And now one of the richest known accumulations of fossil mammals belongs to the middle of the secondary series; and one true mammal has been discovered in the new red sandstone at nearly the commencement of this great series. Cuvier used to urge that no monkey occurred in any tertiary stratum; but now extinct species have been discovered in India, South America, and in Europe even as far back as the eocene stage. The most striking case, however, is that of the Whale family; as these animals have huge bones, are marine, and range over the world, the fact of not a single bone of a whale having been discovered in any secondary formation, seemed fully to justify the belief that this great and distinct order had been suddenly produced in the interval between the latest secondary and earliest tertiary formation. But now we may read in the Supplement to Lyell’s “Manual,” published in 1858, clear evidence of the existence of whales in the upper greensand, some time before the close of the secondary period.

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我再举一例，这是我亲眼看到的，曾大受震动。我在一篇论化石无柄蔓足类的报告里曾说，根据现存的和灭绝的第三纪物种的大量数目，根据全世界——从北极区到赤道——栖息于从高潮线到50英寻各种不同深度区域的许多物种个体数目的异常繁多，根据最古的第三纪层中保存下来的标本的完整状态，根据甚至一个壳瓣（valve）的碎片也容易辨识：根据这一切情况，我曾推论如果无柄蔓足类生存于第二纪，就肯定会保存下来而且被发现；但因为这一时代的岩层中并没有发现过一个物种，我曾断言这一大群是在第三纪的开头突然发展起来的。这使我很痛苦，因为当时我想，这会给一个大群物种的突然出现增加一个事例。但我的著作行将出版的时候，老练的古生物学者波斯开（M．Bosquet）先生寄给我一张完整的标本图，无疑是一种无柄蔓足类，是他亲手从比利时的白垩层中采到的。就好像是为了使此个案尽可能触目惊心，这种蔓足类是属于很普通的、巨大的、遍地存在的一属，即藤壶属，而该属中甚至还没有一个标本在任何第三纪层中发现过。所以我们现在肯定知道蔓足类在第二纪存在过，而这些可能是许多现存第三纪物种的祖先。

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I may give another instance, which from having passed under my own eyes has much struck me. In a memoir on Fossil sessile Cirripedes, I have stated that, from the number of existing and extinct tertiary species; from the extraordinary abundance of the individuals of many species all over the world, from the Arctic regions to the equator, inhabiting various zones of depths from the upper tidal limits to 50 fathoms; from the perfect manner in which specimens are preserved in the oldest tertiary beds; from the ease with which even a fragment of a valve can be recognised; from all these circumstances, I inferred that had sessile cirripedes existed during the secondary periods, they would certainly have been preserved and discovered; and as not one species had been discovered in beds of this age, I concluded that this great group had been suddenly developed at the commencement of the tertiary series. This was a sore trouble to me, adding as I thought one more instance of the abrupt appearance of a great group of species. But my work had hardly been published, when a skilful palaeontologist, M. Bosquet, sent me a drawing of a perfect specimen of an unmistakeable sessile cirripede, which he had himself extracted from the chalk of Belgium. And, as if to make the case as striking as possible, this sessile cirripede was a Chthamalus, a very common, large, and ubiquitous genus, of which not one specimen has as yet been found even in any tertiary stratum. Hence we now positively know that sessile cirripedes existed during the secondary period; and these cirripedes might have been the progenitors of our many tertiary and existing species.

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有关全群物种分明突然出现的情况，古生物学者连篇累牍提到的，就是硬骨鱼类的个案，出现是在白垩纪深处。这一群鱼类包含现存物种的大部分。最近，匹克推特教授将它们的存在往前更加推了半个时期，某些古生物学者认为，某些更加古老的鱼类，其亲缘尚未完全弄清楚的，实际上就是硬骨鱼类。但是，假定如阿加西斯认为的全部硬骨鱼类真是在白垩层开头时出现的，这当然是值得高度注意的事实；除非同样能阐明这一物种群在全世界在同一时期内突然同时出现了，我看它并没有对我的理论造成不可克服的困难。赤道以南并没有发现过任何化石鱼类，对此就不必多说了；而且通读匹克推特的古生物学，当可知道欧洲的几个地质层也只发现过很少物种。少数鱼科现今的分布范围是有限的；硬骨鱼类先前大概也有过相似的有限分布范围，只是在某一个海里大事发展之后，才广泛地分布开来。同时我们也无权假定世界上的海像今天一样从南到北总是自由开放的。甚至在今天，如果马来群岛变为陆地，印度洋的热带部分就会形成一个完全封锁的巨大盆地，那里海产动物的任何大群都可能繁衍起来；直到其中某些物种适应了较冷的气候，并且能够绕过非洲或澳洲的南方海角，因而到达远处的海洋之前，也就局限在那里。

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The case most frequently insisted on by palaeontologists of the apparently sudden appearance of a whole group of species, is that of the teleostean fishes, low down in the Chalk period. This group includes the large majority of existing species. Lately, Professor Pictet has carried their existence one sub-stage further back; and some palaeontologists believe that certain much older fishes, of which the affinities are as yet imperfectly known, are really teleostean. Assuming, however, that the whole of them did appear, as Agassiz believes, at the commencement of the chalk formation, the fact would certainly be highly remarkable; but I cannot see that it would be an insuperable difficulty on my theory, unless it could likewise be shown that the species of this group appeared suddenly and simultaneously throughout the world at this same period. It is almost superfluous to remark that hardly any fossil-fish are known from south of the equator; and by running through Pictet’s Palaeontology it will be seen that very few species are known from several formations in Europe. Some few families of fish now have a confined range; the teleostean fish might formerly have had a similarly confined range, and after having been largely developed in some one sea, might have spread widely. Nor have we any right to suppose that the seas of the world have always been so freely open from south to north as they are at present. Even at this day, if the Malay Archipelago were converted into land, the tropical parts of the Indian Ocean would form a large and perfectly enclosed basin, in which any great group of marine animals might be multiplied; and here they would remain confined, until some of the species became adapted to a cooler climate, and were enabled to double the southern capes of Africa or Australia, and thus reach other and distant seas.

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根据这等考虑，主要是我们对于欧洲和美国以外地方的地质学的无知，近十余年来的发现所掀起的古生物学知识革命，我认为对于全世界生物演替问题进行独断，犹如学者在澳洲的不毛之地待了五分钟就来讨论那里生物的数量和分布范围一样，都是太轻率了。

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From these and similar considerations, but chiefly from our ignorance of the geology of other countries beyond the confines of Europe and the United States; and from the revolution in our palaeontological ideas on many points, which the discoveries of even the last dozen years have effected, it seems to me to be about as rash in us to dogmatize on the succession of organic beings throughout the world, as it would be for a naturalist to land for five minutes on some one barren point in Australia, and then to discuss the number and range of its productions.

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近似物种群在已知的最下化石层中的突然出现。——还有一个相关难点，更加严重。我是指同一群的物种在已知的最下化石岩层中突然出现的情形。使我相信同群的一切现存物种都是从单一的祖先传下来的论据，大多数也同样有力地适用于最早的既知物种。例如，我不能怀疑一切志留纪的三叶虫类（trilobites）都是从某一种甲壳动物传下来的，这种甲壳类一定远在志留纪以前就已生存了，并且和任何既知的动物可能都大不相同。某些最古的志留纪动物，如鹦鹉螺（Nautilus）、海豆芽（Lingula）等等，与现存物种并无多大差异；按照我的理论，不能假设这些古老的物种是所属目的一切物种的原始祖先，因其不具有任何程度的中间性状。而且，即使它们是这些目的祖先，当然也早就被大量的改进后代所淘汰消灭了。

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On the sudden appearance of groups of Allied Species in the lowest known fossiliferous strata.—There is another and allied difficulty, which is much graver. I allude to the manner in which numbers of species of the same group, suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group have descended from one progenitor, apply with nearly equal force to the earliest known species. For instance, I cannot doubt that all the Silurian trilobites have descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed greatly from any known animal. Some of the most ancient Silurian animals, as the Nautilus, Lingula, etc., do not differ much from living species; and it cannot on my theory be supposed, that these old species were the progenitors of all the species of the orders to which they belong, for they do not present characters in any degree intermediate between them. If, moreover, they had been the progenitors of these orders, they would almost certainly have been long ago supplanted and exterminated by their numerous and improved descendants.

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所以，如果我的理论正确，毋庸置疑远在志留纪最下层沉积以前已经过了长久的时期，这与从志留纪到今日的整个时期一样长，或者更长久多了；而且在这样广大的不为人知的时期内，世界上充满了生物。

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Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures.

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至于浩瀚的原始时期内，为什么未发现记录呢？关于这一问题我还不能给予圆满的解答。以默奇森爵士为首的卓越的地质学者坚信，我们在志留纪最下层所看到的生物遗骸，是地球生命的最初曙光。其他极有能力的鉴定者则反对这一结论，如赖尔和福布斯。我们不要忘记，精确知道的，不过是这个世界的一小部分。不久以前，巴兰德（M．Barrande）在志留系之下，增添了另一个更下面的时期，饱含奇特的新物种。他所谓的原生区下面有龙敏德岩层（Longmynd），那里检测到了生命迹象。甚至在某些最低等的无生岩（azoic rock）中，也有磷酸盐结核和沥青物质存在，也许表明该时期曾有生命存在。按照我的理论，志留纪之前无疑在某些地方积累了大堆大堆的含化石岩层，可是要理解它们的不存在谈何容易。如果说那些最古的岩层已经由于剥蚀作用而完全消失，或者说由于变质作用而整个消灭，我们只消在年代继它们之后的地质层中发现微小的残余物，且这残余物应该一般是以变质状态存在的。但是，我们所拥有的关于俄罗斯和北美洲的巨大地面上的志留纪沉积物的描述，并不支持一个地质层越古越蒙受极度的剥蚀和变质作用这样的观点。

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To the question why we do not find records of these vast primordial periods, I can give no satisfactory answer. Several of the most eminent geologists, with Sir R. Murchison at their head, are convinced that we see in the organic remains of the lowest Silurian stratum the dawn of life on this planet. Other highly competent judges, as Lyell and the late E. Forbes, dispute this conclusion. We should not forget that only a small portion of the world is known with accuracy. M. Barrande has lately added another and lower stage to the Silurian system, abounding with new and peculiar species. Traces of life have been detected in the Longmynd beds beneath Barrande’s so-called primordial zone. The presence of phosphatic nodules and bituminous matter in some of the lowest azoic rocks, probably indicates the former existence of life at these periods. But the difficulty of understanding the absence of vast piles of fossiliferous strata, which on my theory no doubt were somewhere accumulated before the Silurian epoch, is very great. If these most ancient beds had been wholly worn away by denudation, or obliterated by metamorphic action, we ought to find only small remnants of the formations next succeeding them in age, and these ought to be very generally in a metamorphosed condition. But the descriptions which we now possess of the Silurian deposits over immense territories in Russia and in North America, do not support the view, that the older a formation is, the more it has suffered the extremity of denudation and metamorphism.

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目前这种个案还无法解释，因而真的会被当作有力的论据来反对本书所持的观点。为了指出下文可能得到某种解释，我提出以下的假说。根据欧洲和美国各地质层中生物遗骸的性质——它们似乎没有在深海中栖息过，并且根据构成地质层的厚达数英里的沉积物的量，我们可以推论产生沉积物的大岛屿或大陆地，始终是处在欧洲和北美洲的现存大陆附近。但是我们不知道在若干连续地质层之间的间隔期间，事物的状态曾经是怎样的；不知道欧洲和美国在这些间隔期间究竟是干燥的陆地，还是没有沉积物的近陆海底，还是广阔的、深不可测的海底。

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The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained. To show that it may hereafter receive some explanation, I will give the following hypothesis. From the nature of the organic remains, which do not appear to have inhabited profound depths, in the several formations of Europe and of the United States; and from the amount of sediment, miles in thickness, of which the formations are composed, we may infer that from first to last large islands or tracts of land, whence the sediment was derived, occurred in the neighbourhood of the existing continents of Europe and North America. But we do not know what was the state of things in the intervals between the successive formations; whether Europe and the United States during these intervals existed as dry land, or as a submarine surface near land, on which sediment was not deposited, or again as the bed of an open and unfathomable sea.

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看看现今的海洋，是陆地的三倍，还散布着许多岛屿；但我们知道，几乎没有一个真正的海洋岛提供过一件古生代或第二纪地质层的残余物。因此，也许可以推论，在古生代和第二纪，大陆和大陆岛屿没有在今日海洋的范围内存在过；因为，如果存在过，那么古生代层和第二纪层就大有可能由它们磨损的沉积物堆积起来，且由于在非常长久时期内肯定会发生水平面的波动，至少有一部分隆起了。于是，如果这等事实有推论价值，那么就可以推论，在现今海洋展开的范围内，自从有任何记录的最古远时代以来，都是海洋的存在；另一方面也可以推论，在现今大陆存在的处所，也是大片陆地的存在，自从志留纪以来无疑遭受了巨大的水平面波动。我论珊瑚礁一书中所附的彩色地图，使我做出结论，各大洋至今依然是沉陷的主要区域，大的群岛依然是水平面波动的区域，大陆依然是上升的区域。但是我们有权设想，自远古以来事情就是这样的吗？大陆的形成，似乎由于多次水平面波动，上升力量占优势所致；但优势运动的地域，难道在时代的推移中没有变化吗？远在志留纪以前的一个时期，现今海洋展开的处所，也许有大陆存在，而现今大陆存在的处所，也许有清澈广阔的海洋存在。例如，如果太平洋海底现在变为大陆，就算那里有比志留纪层还古的沉积层曾经沉积下来，我们也无权假定应该在那里找到它们。因为这些地层，由于沉陷数英里到更接近地心的地方，并且由于上面有水的非常巨大的压力，很可能比始终接近地球表面的地层要遭受远为严重的变质作用。世界上某些地方裸露变质岩的广大区域，如南美洲，一定曾在巨大压力下遭受过灼热，我总觉得这等区域需要专门的解释；大概可以相信，在这广大区域里可以看到许多远在志留纪以前的地质层是处在完全变质的状态之下的。

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Looking to the existing oceans, which are thrice as extensive as the land, we see them studded with many islands; but not one oceanic island is as yet known to afford even a remnant of any palaeozoic or secondary formation. Hence we may perhaps infer, that during the palaeozoic and secondary periods, neither continents nor continental islands existed where our oceans now extend; for had they existed there, palaeozoic and secondary formations would in all probability have been accumulated from sediment derived from their wear and tear; and would have been at least partially upheaved by the oscillations of level, which we may fairly conclude must have intervened during these enormously long periods. If then we may infer anything from these facts, we may infer that where our oceans now extend, oceans have extended from the remotest period of which we have any record; and on the other hand, that where continents now exist, large tracts of land have existed, subjected no doubt to great oscillations of level, since the earliest silurian period. The coloured map appended to my volume on Coral Reefs, led me to conclude that the great oceans are still mainly areas of subsidence, the great archipelagoes still areas of oscillations of level, and the continents areas of elevation. But have we any right to assume that things have thus remained from eternity? Our continents seem to have been formed by a preponderance, during many oscillations of level, of the force of elevation; but may not the areas of preponderant movement have changed in the lapse of ages? At a period immeasurably antecedent to the silurian epoch, continents may have existed where oceans are now spread out; and clear and open oceans may have existed where our continents now stand. Nor should we be justified in assuming that if, for instance, the bed of the Pacific Ocean were now converted into a continent, we should there find formations older than the silurian strata, supposing such to have been formerly deposited; for it might well happen that strata which had subsided some miles nearer to the centre of the earth, and which had been pressed on by an enormous weight of superincumbent water, might have undergone far more metamorphic action than strata which have always remained nearer to the surface. The immense areas in some parts of the world, for instance in South America, of bare metamorphic rocks, which must have been heated under great pressure, have always seemed to me to require some special explanation; and we may perhaps believe that we see in these large areas, the many formations long anterior to the silurian epoch in a completely metamorphosed condition.

55
-

这里所讨论的几个难点是，在连续的地质层中许多介于现今生存和既往曾经生存的物种之间，并没有发现无数的过渡环节；欧洲的地质层中，有成群的物种突然出现；按现在所知，志留纪层以下几乎全无含化石地质层——这一切无疑都是性质极其严重的难点。所有最卓越的古生物学者，即居维叶、欧文、阿加西斯、巴兰德、福尔克纳、福布斯等，以及所有最伟大的地质学者，如赖尔、默奇森、塞奇威克等，都一致而且常常猛烈地坚持物种的不变性。因此，我们清楚地看到上述难点的严重性了。但是，我有理由相信，大权威赖尔爵士经过进一步斟酌，对于这个主题持严重的怀疑了。我觉得跟这些大权威分庭抗礼不胜唐突之至，我跟其他人一样，所有的知识都归功于他们。那些认为自然地质记录多少是完全的人们，不重视本书提出的其他事实和论据的人们，无疑会毫不犹豫地反对我的理论的。至于我自己，则遵循赖尔的比喻，把自然地质的记录看作是一部已经散失不全，并且用变化着的方言写成的世界历史；在这部历史中，我们只有最后的一卷，而且只涉及两三个国家。在这一卷中，又只是在这里或那里保存了一个短章；每页只有寥寥几行。慢慢变化着的史家语言的每个字，在断断续续的各章中又多少有些不同，可能表达了埋藏在连续而相互隔开的地质层中的、表面上突变的诸生物类型。按照这种观点，上面所讨论的难点就可以大事化小，小事化无了。

55
-

The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature. We see this in the plainest manner by the fact that all the most eminent palaeontologists, namely Cuvier, Owen, Agassiz, Barrande, Falconer, E. Forbes, etc., and all our greatest geologists, as Lyell, Murchison, Sedgwick, etc., have unanimously, often vehemently, maintained the immutability of species. But I have reason to believe that one great authority, Sir Charles Lyell, from further reflexion entertains grave doubts on this subject. I feel how rash it is to differ from these great authorities, to whom, with others, we owe all our knowledge. Those who think the natural geological record in any degree perfect, and who do not attach much weight to the facts and arguments of other kinds given in this volume, will undoubtedly at once reject my theory. For my part, following out Lyell’s metaphor, I look at the natural geological record, as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines. Each word of the slowly-changing language, in which the history is supposed to be written, being more or less different in the interrupted succession of chapters, may represent the apparently abruptly changed forms of life, entombed in our consecutive, but widely separated formations. On this view, the difficulties above discussed are greatly diminished, or even disappear.

1 ..... 10 11 12 13 14 15
序号 英文/音标 中文解释 更多操作

extinct

[ɪk’stɪŋkt]

adj.灭绝的;熄灭的;消亡的

lapse

[læps]

n.过失;流逝;间隔;堕落;失效

infer

[ɪn’fɜː(r)]

vt.推断;猜测;暗示

deposition

[ˌdepə’zɪʃn]

n.沉积

enumerate

[ɪ’njuːməreɪt]

vt.数;列举;枚举

transitional

[træn’sɪʃənl]

adj.变化的;过渡期的;过渡性的

moisture

[’mɔɪstʃə(r)]

n.水分;潮气;湿度

lesser

[’lesə(r)]

adj.较少的;较小的;次要的

exterminate

[ɪk’stɜːmɪneɪt]

vt.消灭;扑灭;根绝

modification

[ˌmɒdɪfɪ’keɪʃn]

n.修改;修正;修饰

continual

[kən’tɪnjuəl]

adj.不断的;频繁的;连续的

Geology

[dʒi’ɒlədʒi]

n.地质学;(某地区的)地质情况;地质学的著作

wholly

[’həʊlli]

adv.完全地;全部地;一概

descendant

[dɪ’sendənt]

n.后裔;子孙;后代

enlarge

[ɪn’lɑːdʒ]

v.扩大;增大;详述

indirect

[ˌɪndə’rekt]

adj.间接的;迂回的

genus

[’dʒiːnəs]

n.【生物学】属;类;种;型

converge

[kən’vɜːdʒ]

vi.聚合;集中;会聚

Independently

[ˌɪndɪ’pendəntli]

adv.独立地;自立地

infinite

[’ɪnfɪnət]

adj.无穷的;无限的

suffice

[sə’faɪs]

vi.足够;使满足

past

[pɑːst]

a. 过去的;

treatise

[’triːtɪs]

n.论文;论述;故事

inadequate

[ɪn’ædɪkwət]

adj.不适当的;不充分的

duration

[dju’reɪʃn]

n.持续时间

superimpose

[ˌsuːpərɪm’pəʊz]

vt.置于某物之上;添加

grind

[ɡraɪnd]

v.磨;压迫;碾碎;磨得吱吱响;逐渐停顿

sediment

[’sedɪmənt]

n.沉淀物

degradation

[ˌdeɡrə’deɪʃn]

n.降低;堕落;退化

pebble

[’pebl]

n.鹅卵石

atom

[’ætəm]

n.原子

boulder

[’bəʊldə(r)]

n.大圆石;巨砾

clothe

[kləʊð]

vt.穿上;赋予

rocky

[’rɒki]

adj.岩石的;像岩石的;坚硬的;麻木的;困难重重的;摇晃的，不稳定的

vegetation

[ˌvedʒə’teɪʃn]

n.植物;草木

elapse

[ɪ’læps]

v.逝去;过去

Miller

[’mɪlə(r)]

n.磨坊主;碾磨工;【机】铣床;【昆】蛾

conglomerate

[kən’ɡlɒmərət]

n. (房子等)密集物;

thickness

[’θɪknəs]

n.厚度;浓度;层

stamp

[stæmp]

【1】 n.邮票; 图章【2】v.盖邮戳,盖印章

sedimentary

[ˌsedɪ’mentri]

adj.沉积的;沉淀性的;沉淀作用造成的

crust

[krʌst]

n.外壳;坚硬的外壳;面包皮

igneous

[’ɪɡniəs]

adj.(指岩石)火成的;火的;似火的

geologist

[dʒi’ɒlədʒɪst]

n.地质学家

lofty

[’lɒfti]

adj.高的;崇高的;高尚的;傲慢的

estimative

[’estɪmət]

n.估价;估计

independently

[ˌɪndɪ’pendəntli]

adv.独立地;自立地

volcanic

[vɒl’kænɪk]

adj.火山的;猛烈的

pare

[peə(r)]

v.削减;剥或削(某物)的皮;修剪(某物)边缘

perpendicular

[ˌpɜːpən’dɪkjələ(r)]

adj.垂直的;直立的;陡峭的

dislocation

[ˌdɪslə’keɪʃn]

n.【医】脱臼

displacement

[dɪs’pleɪsmənt]

n.置换;转位;移动

endeavor

[ɪn’devə]

n.尽力;努力

tempting

[’temptɪŋ]

adj.诱惑人的,

escarpment

[ɪ’skɑːpmənt]

n.长而陡的坡或悬崖

dome

[dəʊm]

n. 圆屋顶；圆盖;

overlie

[ˌəʊvə’laɪ]

v.躺在……上;覆闷致死

thinner

[’θɪnə(r)]

稀释剂

denude

[dɪ’njuːd]

vt.剥光;剥蚀

crude

[kruːd]

adj.天然的;未加工的;粗糙的

allowance

[ə’laʊəns]

n.津贴

breakage

[’breɪkɪdʒ]

n.破损;打破;破坏

indent

[ɪn’dent]

n.订货单

nodule

[’nɒdjuːl]

n.【医】小瘤;小结节

breakwater

[’breɪkwɔːtə(r)]

n.防波堤

ample

[’æmpl]

adj.丰富的;宽敞的;充足的

submerge

[səb’mɜːdʒ]

vt.使浸没;潜入水中;覆盖

probability

[ˌprɒbə’bɪləti]

n.可能性

imperfect

[ɪm’pɜːfɪkt]

adj.不完美的;有缺点的;未完善的

specimen

[’spesɪmən]

n.标本;样本

decay

[dɪ’keɪ]

v.(使)衰退

tacit

[’tæsɪt]

adj.心照不宣的;缄默的;默示的

tint

[tɪnt]

n. 色彩; 浅色; 染发剂

embed

[ɪm’bed]

v.(使)插入;(使)嵌入;深留脑中

gravel

[’ɡrævl]

n.碎石

percolation

[ˌpɜːkə’leɪʃn]

n.过滤;浸透

littoral

[’lɪtərəl]

adj.海岸的;沿海的

Mediterranean

[ˌmedɪtə’reɪniən]

adj.地中海的

inhabit

[ɪn’hæbɪt]

v.居住于;占据;栖息

whereas

[ˌweər’æz]

conj.然而;鉴于

hitherto

[ˌhɪðə’tuː]

adv.到目前为止;迄今

terrestrial

[tə’restriəl]

adj.陆地的;陆生的;地球的

fragmentary

[’fræɡməntri]

adj.碎片的;碎块的;碎屑状的;零碎的;不完全的

preservation

[ˌprezə’veɪʃn]

n.保存

tabulate

[’tæbjuleɪt]

v.制成表;使成平面

skilful

[’skɪlfl]

adj.熟练的;巧妙的;技术好的.

barren

[’bærən]

adj.贫瘠的;无效的;不育的

ascertain

[ˌæsə’teɪn]

vt.确定;查明;探知

invariably

[ɪn’veəriəbli]

adv.不变地;总是;一贯地

intermittent

[ˌɪntə’mɪtənt]

adj.间歇的;断断续续的

Scarcely

[’skeəsli]

adv.几乎不;简直不;刚刚;决不

fauna

[’fɔːnə]

n.(某地区或某时期的)所有动物

muddy

[’mʌdi]

adj.泥泞的;浑浊的;糊涂的

gradual

[’ɡrædʒuəl]

adj.逐渐的;逐步的;平缓的

oscillation

[ˌɒsɪ’leɪʃn]

n.振动

stationary

[’steɪʃənri]

adj.静止的

alternate

[’ɔːltɜːnət]

v.交替;轮流

elevation

[ˌelɪ’veɪʃn]

n.提升

accordance

[ə’kɔːdns]

n.一致;符合

inculcate

[’ɪnkʌlkeɪt]

vt.谆谆教诲;教育

adjoin

[ə’dʒɔɪn]

v.邻接;毗连

shoal

[ʃəʊl]

浅滩

commencement

[kə’mensmənt]

n.开始;毕业典礼

proportional

[prə’pɔːʃənl]

adj.成比例的;相称的

rash

[ræʃ]

n.疹子;大量

correlate

[’kɒrəleɪt]

vt.使相互关联

immigrate

[’ɪmɪɡreɪt]

v.移居入境

earlier

[’ɜːlɪə]

adj.早的;初期的

latest

[’leɪtɪst]

adj.最近的;最新的

converse

[kən’vɜːs]

n.相反的事物;逆命题

Glacial

[’ɡleɪʃl]

adj.冰川(期)的;非常冷的;缓慢的;(人)态度不友善的

inordinate

[ɪn’ɔːdɪnət]

adj.过度的;非常的;无法无天的

glacial

[’ɡleɪʃl]

adj.冰川(期)的;非常冷的;缓慢的;(人)态度不友善的

epoch

[’iːpɒk]

n. 时期; 时代; 新纪元; 划时代的大事; 世

gradation

[ɡrə’deɪʃn]

n.渐变;阶段;等级;刻度;元音交替

counterbalance

[ˌkaʊntə’bæləns]

n.平衡;平衡力

re-cover

[ˌriː’kʌvə(r)]

v.再覆盖;装以新的封面或盖

upright

[’ʌpraɪt]

adj.直立的;垂直的;正直的

reappear

[ˌriːə’pɪə(r)]

v.再出现

naturalist

[’nætʃrəlɪst]

n.自然主义者;博物学者

founding

[’faʊndɪŋ]

n.建立;成立,

locomotive

[ˌləʊkə’məʊtɪv]

n.火车头

lessen

[’lesn]

v.减少;减轻

scarcely

[’skeəsli]

adv.几乎不;简直不;刚刚;决不

imaginary

[ɪ’mædʒɪnəri]

adj.想象的;虚构的

Cape

[keɪp]

n.岬;海角

submarine

[ˌsʌbmə’riːn]

n.潜水艇

chiefly

[’tʃiːfli]

adv.主要地

descent

[dɪ’sent]

n.下降;下坡;家世;血统;侵袭;衰落;继承

progenitor

[prəʊ’dʒenɪtə(r)]

n.祖先;先驱

multiply

[’mʌltɪplaɪ]

vt.乘;增加

multiplication

[ˌmʌltɪplɪ’keɪʃn]

n.增加;繁殖;乘法运算

succession

[sək’seʃn]

n.连续;继承权;继位

comparative

[kəm’pærətɪv]

adj.比较的;相当的

liable

[’laɪəbl]

a. 有(法律)责任的；有义务的;

sandstone

[’sændstəʊn]

n.砂岩

earliest

[’ɜːliɪst]

n.最早

Arctic

[’ɑːktɪk]

adj.北极的;极寒的

equator

[ɪ’kweɪtə(r)]

n.赤道

tidal

[’taɪdl]

adj.潮的;潮水似的

fathom

[’fæðəm]

n.英寻(=6英尺)vi.测量深度vt.彻底了解;测深

extract

[’ekstrækt]

vt.摘录;提取

affinity

[ə’fɪnəti]

n.姻亲;密切关系;吸引力

simultaneous

[ˌsɪml’teɪniəs]

adj.同时发生的;同步的

enclose

[ɪn’kləʊz]

vt.圈起;围住;附上;封入

basin

[’beɪsn]

n.脸盆;水池

cooler

[’kuːlə(r)]

n.冷却器

cape

[keɪp]

n.岬;海角

Africa

[’æfrɪkə]

n.非洲

ignorance

[’ɪɡnərəns]

n.无知;愚昧

geology

[dʒi’ɒlədʒi]

n.地质学;(某地区的)地质情况;地质学的著作

allude

[ə’luːd]

v.暗示;暗指

supplant

[sə’plɑːnt]

v. 取代; 排挤根除

swarm

[swɔːm]

n.群;蜂群

eminent

[’emɪnənt]

adj.著名的;卓越的

competent

[’kɒmpɪtənt]

adj.有能力的;足够的;胜任的

abound

[ə’baʊnd]

v.富于;充满

phosphatic

[fɒs’fætɪk]

adj.磷酸盐的;含磷酸盐的

bituminous

[bɪ’tjuːmɪnəs]

adj.含沥青的

metamorphic

[ˌmetə’mɔːfɪk]

adj.变性的;变态的;【地】变质的

remnant

[’remnənt]

n.残余;残剩余;残存者;零头

metamorphism

[ˌmetə’mɔːfɪzəm]

n.变形;变质;变态

entertain

[ˌentə’teɪn]

v.娱乐;使有兴趣;招待;考虑;抱有;容纳

tract

[trækt]

n.大片土地;器官系统

stud

[stʌd]

n.大头钉;饰钉;立柱;板墙筋;壁骨;种马;耳环;年轻男子

continental

[ˌkɒntɪ’nentl]

adj.大陆的;欧洲大陆的

append

[ə’pend]

vt.附加;添加

subside

[səb’saɪd]

vi.沉没;平息;下陷

unanimous

[ju’nænɪməs]

adj.全体一致的;一致同意的

vehement

[’viːəmənt]

adj.感情强烈的;猛烈的

undoubted

[ʌn’daʊtɪd]

adj.无疑的

dialect

[’daɪəlekt]

n.方言;地方话

fossiliferous

[ˌfɒsɪ’lɪfərəs]

adj.含有化石的

undoubted

[ʌn’daʊtɪd]

adj.无疑的

Falconer

[’fɔːlkənə(r)]

n.以鹰狩猎者;饲养和训练猎鹰的人

geologist

[dʒi’ɒlədʒɪst]

n.地质学家

immutability

[ɪˌmjuːtə’bɪləti]

n.不变;不变性

entertain

[ˌentə’teɪn]

v.娱乐;使有兴趣;招待;考虑;抱有;容纳

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