Geological formation

“ 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. ”

“ On the three principal tests of relative age — superposition, mineral character, and fossils — Change of mineral character and fossils in the same continuous formation — Proofs that distinct species of animals and plants have lived at successive periods — Distinct provinces of indigenous species — Great extent of single provinces — Similar laws prevailed at successive geological periods — Relative importance of mineral and palæontological characters — Test of age by included fragments — Frequent absence of strata of intervening periods — Principal groups of strata in western Europe. ”

“ For thirty years Geology has been gradually establishing, by evidence the fulness and accuracy of which are truly amazing, the regularity in the sequence of the geological formations, and distinguishing, with ever-increasing precision, the specific differences of the animals and plants contained in these accumulations of past ages. ”

“ When very widely separated, the species of fossils may not be identical, but so very similar that they are regarded as equivalent species. The identification of formations consists in the identification of fossils. It is for this purpose mainly that fossils are regarded as of so great importance.
6. If each formation is characterized by the presence of new species, it follows that the work of creation was a progressive one, continued through long periods of time. The latest creation of which we have any geological evidence is that of man. ”

“ To this day the fundamental principle guiding our identification of geological formations in different ages rests upon the assumption that each period has had one character throughout; whereas the progress of geology is daily pressing upon us the evidence that at each period different latitudes and different continents have always had their characteristic animals and plants, if not as diversified as now, at least varied enough to exclude the idea of uniformity. ”

“ When we discover a constant and regular assemblage of organic Remains, commencing with one series of strata, and ending with another, which contains a different assemblage, we have herein the surest grounds whereon to establish those Divisions which are called geological formations, and we find many such Divisions succeeding one another, when we investigate the mineral deposites on the surface of the Earth. ”

“ From the point where the geological formations approach the present time, plant and animal geography also assists geology in increasing the weight of the reasons for an origin of organisms through descent. With the tertiary period, the fauna and flora of the globe, which in former periods had a nearly uniform character all over the earth and showed no climatic differences, begin to separate according to climate, zones, and greater continents. ”

“ The principles of physics and the succession of geological formations with their fossils, the classification and distribution of plants and animals must be taught elsewhere; but much profit may be had from terrestrial phenomena by which the principles of physics are illustrated, and from the consequences of past geological changes in determining present geographical conditions, and especially from the physiographic controls by which the distribution of organic forms is determined. ”

“ The geologist, in his attempts to collate the Divine with the geologic record, has, I repeat, only three of the six periods of creation to account for,—the period of plants, the period of great sea monsters and creeping things, and the period of cattle and beasts of the earth. He is called on to question his systems and formations regarding the remains of these three great periods, and of these only. And the question once fairly stated, what, I ask, is the reply? All geologists agree in holding that the vast geological scale naturally divides into three great parts. ”

“ These rocks contain the fossiliferous and organic remains of the early and primitive inhabitants of the earth, and indicate the order of man's moral and intellectual development; for as each successive layer or stratum of fossiliferous rocks, in which the organic remains of man are found, marks a distinct period in his history, and the growth of his moral and intellectual brain is found in all cases to correspond to the age and growth of these strata, the question is thus settled and demonstrate! by the facts of geological science. ”

“ Such effects, though attributable mainly to man, are produced in some degree by all other animals.
Besides these general effects, it is the existence of organic forms that has conferred on all the sedimentary rocks their fossiliferous character. The records of the climate of each geological period, of the physical geography, of the vegetable productions, and of the animal forms by which the earth was peopled, consist in the remains of the living beings of these several periods, imbedded in the contemporaneous rock formations. ”

“ GEOLOGY, n. The science of the earth's crust -- to which, doubtless, will be added that of its interior whenever a man shall come up garrulous out of a well. The geological formations of the globe already noted are catalogued thus: The Primary, or lower one, consists of rocks, bones or mired mules, gas-pipes, miners' tools, antique statues minus the nose, Spanish doubloons and ancestors. The Secondary is largely made up of red worms and moles. ”

“ T THE problem of the origin of the earth is essentially astronomical rather than geological, because geological history is considered to have begun when common earth processes, such as erosion, deposition, and transportation of sediments, etc., were brought into play. ”

“ A species which has once died out does not seem ever to have reappeared.
4. When the order of succession of organic remains among the stratified rocks has been determined, they become an invaluable guide in the investigation of the relative age of rocks and the structure of the land. Each zone and formation, being characterized by its own species or genera, may be recognized by their means, and the true succession of strata may thus be confidently established even in a country wherein the rocks have been shattered by dislocation, folded, inverted or metamorphosed. ”

“ Speculative geology is romance, and does not merit the name of science; yet is science obliged to borrow her theory of soils. The alternation of heat and cold, moisture and dryness, decomposed the mountains of primitive, secondary and tertiary formation; rains, and the laws of gravity, brought these from places of more, to places of less elevation—where, by mechanical mixture and chymical combination, the present substrata were formed. ”

“ Thus our knowledge of Epochs of Life, and indeed of the whole geological history of the earth, is based on the superposition of beds in the earth’s crust, and on the diversity of fossil remains in the successive beds so superimposed on each other ”

“ Besides, such a collocation affords a sufficient period for the development of the rich and characteristic fauna and flora of the forest-bed—a widespread fossiliferous and carbonaceous deposit that must represent a lapse of time of geological importance. ”

“ But modern observations have tended continually to dispel this delusion, and the geologist is now convinced that at no given era of the past have the boundaries of land and sea, or the height of the one and depth of the other, or the geographical range of the species inhabiting them, whether of animals or plants, become fixed and unchangeable. ”

“ When we reflect, therefore, on the fractional state of the annals which are handed down to us, and how little even these have as yet been studied, we may wonder that so many geologists should attribute every break in the series of strata, and every gap in the past history of the organic world, to catastrophes and convulsions of the earth's crust, or to leaps made by the creational force from species to species, or from class to class. ”

“ We shall see fossil shells best on the weathered surfaces of rocks, i.e., surfaces which have been exposed to the weather. One beginning geological study will probably think we shall find fossils best by looking at fresh broken surfaces of rock. This is not so. If you want to find fossils, look at the rock where it has been exposed to the weather. The action of the weather—rain, carbonic dioxide in the rain water, etc.—is to sculpture the surface of the rock, so that the fossils stand out in relief. ”

“ The subjects I first propose to consider have no general name, and are not easily grouped under a single descriptive heading; but they may be compared with that recent development of a sister science which has been termed surface-geology or Earth-sculpture. In the older geological works we learnt much about strata, and rocks, and fossils, their superposition, contortions, chemical constitution, and affinities, with some general notions of how they were formed in the remote past ”

“ I. There is one important deduction to be established from these investigations which meets us at the threshold of the inquiry, namely, that geology clearly and distinctly shows there is a beginning to the course of creation as respects the crust of the earth and its organic forms of life. The stratified rocks all manifest succession in their order of deposition, and, therefore, also succession in time. Some are prior to and older in formation than others ”

“ There would, however, be this difference in the cases:—the races of animals and plants of this modern period of the globe are more various in different countries than the fossils of any one older geological period appear to have been; there is now more of local diversity in organic life upon the globe, than formerly obtained; and from this we infer that the physical conditions of the globe in former periods were more general —more uniform over large areas than at present. ”

“ Though perfectly adequate forty years ago, it has been greatly outgrown by the progress of geological discovery, and is, as I have said, adequate no longer; and it becomes a not unimportant matter to determine the special scheme that would bring into completest harmony the course of creation, as now ascertained by the geologist, and that brief but sublime narrative of its progress which forms a meet introduction in Holy Writ to the history of the human family. ”

“ We know that arctic and temperate faunas and floras flourished during interglacial times, and a like succession of life-forms followed the final disappearance of glacial conditions. A study of the organic remains met with in any particular deposit will not necessarily, therefore, enable us to assign these to their proper horizon. ”

“ Since the publication of Professor George Darwin’s masterly paper on the influence of geological changes on the earth’s axis of rotation, geologists have felt assured that the great climatic revolutions to which the stratified rocks bear witness must be otherwise explained than by a wandering of the pole. ”

“ The geologist is familiar with the fact, that in one formation he may have before him chiefly oceanic and deep-sea deposits, and in another those of the shallower waters, and that alternations of these may, in the same age or immediately succeeding ages, present very different groups of fossils. ”

“ Variation and natural selection would also afford a key to a multitude of geological facts otherwise wholly unaccounted for, as, for example, why there is generally an intimate connection between the living animals and plants of each great division of the globe and the extinct fauna and flora of the post-tertiary or tertiary formations of the same region; ”

“ This system of classification is not only recommended by its greater clearness and facility of application, but is also best fitted to strike the imagination by bringing into one view the past changes of the inorganic world, and the contemporaneous revolutions of the organic creation. For the sedimentary formations of successive periods are most readily distinguished by the different species of fossil animals and plants which they inclose, and of which one race after another has flourished and then disappeared from the earth. ”

“ By noting the fossil contents of a formation, therefore, even in a district where the rocks have been so disturbed that their sequence is otherwise untraceable, the geologist can confidently assign their relative position to each of the fractured masses. ”