Crust

“ Hitherto we have spoken of the earth’s crust without reference to that wondrous succession and development of living beings which once had their joy of life, and whose fossil remains, found in the different strata, waken such kindling emotions of the power of Deity, and enlarge indefinitely our conceptions of the boundless resources of His Mind. ”

“ The crust must be regarded as in a perpetual state of strain, and its component materials are therefore subject to all the effects which flow from that condition. It is the one great object of the geotectonic division of geology to study the structures which have been developed in consequence of earth-movements, and to discover from this investigation the nature of the processes whereby the rocks of the crust have been brought into the condition and the positions in which we now find them. ”

“ The crust of the Earth, which may scarcely have been perceptibly elevated by the sudden and repeated, or almost uninterrupted shocks by which it has been moved from below, undergoes, nevertheless, great changes in the course of centuries in the relations of the elevation of solid portions, when compared with the surface of the liquid parts, and even in the form of the bottom of the sea. ”

“ The subsequent changes which the earth's crust has undergone—aqueous, volcanic, and organic—the working up of the conglomerates and sandstones, the depositing of the deep-sea beds, the overflowing of the traps and lavas, the storing away of the carboniferous treasures, are all the story of every hand-book of geology, and pertain no more to one theory than another of the origin of the rocks. ”

“ The whole surface of the earth,—I speak broadly, and leave out minor qualifications,—is made up of such layers of mud, so hard, the majority of them, that we call them rock whether limestone or sandstone, or other varieties of rock. And, seeing that every part of the crust of the earth is made up in this way, you might think that the determination of the chronology, the fixing of the time which it has taken to form this crust is a comparatively simple matter. ”

“ As the nucleus contracts, it tends to draw away from the cooled and solid crust, and the latter settles, adapting itself to the shrinking nucleus much as the skin of a withering apple wrinkles down upon the shrunken fruit. The unsupported weight of the spherical crust develops enormous tangential pressures, similar to the stresses of an arch or dome, and when these lateral thrusts accumulate beyond the power of resistance the solid rock is warped and folded and broken. ”

“ The fire, by melting the [145] matter, produced a vitrified crust, and the basis of all the matter which composes the globe is glass, of which sand and gravel are only fragments. The other kinds of earth are formed from a mixture of this sand, with fixed salts and water, and when the crust cooled, the humid particles, which were raised in form of vapours, refel, and formed the sea. They at first covered the whole surface, and even surmounted the highest mountains. ”

“ Francisco and Messina, this form of disturbance of the earth's crust is growing constantly less frequent. The earth is growing cooler as it grows older; the crust thickens and grows stronger as centuries pass. We have been studying the earth only a few hundred years. The crust has been cooling for millions of years, and mountain-making was the result of the shrinking of the crust. That formed folds and clefts, and let masses of the heated substance pour out on the surface. ”

“ A striking fact in the configuration of the crust is that each continent, or elevated mass of the crust, is diametrically opposite to an ocean basin or great depression; the only partial exception being in the case of southern South America, which is antipodal to eastern Asia. Professor C. Lapworth has Arrangement of world-ridges and hollows.generalized the grand features of crustal relief in a scheme of attractive simplicity. He sees throughout all the chaos of irregular crust-forms the recurrence of a certain harmony, a succession of folds or waves which build up all the minor features. ”

“ The superficial crust of the earth,—by which is meant only that film, compared with its diameter, which is represented by a few miles in depth—is composed of distinct mineral masses, exhibiting peculiar physical conditions and a certain order of arrangement. These rocks appear to have resulted from two dissimilar causes; in one class the action of heat is evident, and in the other we have either the slow deposition of matter suspended in water, or crystallization from solution; an aqueous origin is indicated by peculiarities of formation in all the more recent rocks. ”

“ The solidified crust, when cooled to the temperature derived from the joint influence of the hot sun and the cold regions around the globe, suffers no further loss of heat; but the internal parts may still grow cooler through immense periods of time; they may thus contract more than the outer parts, and fail to sustain them; fractures follow, and the equilibrium of pressure is restored, till a long period of cooling revives the irregularity of forces, and the crust breaks again. ”

“ All these circumstances are the natural consequences of extensive depression of the crust of the globe, followed by elevations; both being determined in greater intensity to points, lines, and areas of weakness, in a solid crust above a fluid of small compressibility, like melted rock. ”

“ By virtue of the force of gravity pervading her whole frame, the crust of the earth is continually undergoing changes, as the loss of heat and consequent contraction, or chemical changes beneath the surface, leave room for the movement inward of the rock-substances of the crust, with crushing, grinding action, and the generation of intense heat. ”

“ For untold millions of years the rocks at and near the earth’s surface have been crumbling; streams have been incessantly sawing into the lands; the sea has been eating into continental masses; the winds have been sculpturing desert lands; and, more intermittently and locally, glaciers have plowed through mountain valleys, and even great sheets of ice have spread over considerable portions of continents. Throughout geologic time, the crust of the earth has shown marked instability. ”

“ The causes and mode of operation of the great movements of the earth's crust which have produced mountains, plains and table-lands, are still involved in some mystery. One patent cause is the unequal settling of the crust towards the centre; but it is not so generally understood as it should be, that the greater settlement of the ocean-bed has necessitated its pressure against the sides of the continents in the same manner that a huge ice-floe crushes a ship or a pier. ”

“ The contraction of the earth's interior by cooling and by the emission of material from below the over-crust, has caused this crust to press downward, and therefore laterally, and so to effect great bends, folds, and plications; and these, modified subsequently by surface denudation, and the piling of sediments on portions of the crust, constitute mountain chains and continental plateaus. ”

“ We have found that the entire crust of the globe, many miles in thickness, and probably to its centre, has been dissolved by heat, and much of it also by water; that a large part of it, at least, has, by the same chemistry, been made to constitute portions of the animal frame ”

“ There can be no real contradiction between the truth of Scripture and the truth of Science. Whatever is true in one department of God’s agency, must be true when compared with his works in any other department. As an illustration we may notice one particular in which Geology and Scripture move towards the same point in proving the recent introduction of man. We take up a chart of the earth’s crust, and examine it so far as that crust is open to our investigation: eight miles depth or height we know pretty accurately, and in all these accumulations we find one concurrent testimony. ”

“ Such gradual, quiet movements of the earth’s crust not only modify the outline of coasts, as we have seen, but are of far greater geological importance in that they permit the making of immense deposits of stratified rock. ”

“ These cavities will continue to increase, will become of huge magnitude when the outside crust grows thick enough to form its own supporting arch, for then the fused interior will recede, and form mighty vaults that will engulf not the waters merely, but all the atmosphere likewise. ”

“ For millions of years it continued to revolve as a ball of liquid—still -95- cooling—still being pressed very hard at its central parts by the weight of all the gases and liquids round it, till at last the first crust of solid matter began to form on the liquid surface. This crust continued to thicken, but it was subject to many appalling catastrophes and breakages.
We have already used the occurrence of the tides of the earth as an instance of the Sun's attraction. The Sun (and the Moon) attract the waters of the earth, pulling them up towards themselves. ”

“ Certainly our machine had risen easily enough through the purple rocks below us. The scientific aspects of that second crust about the earth have been considered very carefully, and the best scientific opinions have been sought.
Mankind dwells upon a comparatively thin crust about the molten or plastic interior of the earth. It would seem there is a similar crust about the air. Science long ago had evidence of it in the reflection of radio waves by the so-called Heaviside Layer. ”

“ Under the enormous pressure of this atmosphere the liquid surface of the earth solidified at very high temperature. Whether the earth's mass solidified from the centre outward or by forming a solid crust over a liquid interior, is a question to be decided by physicists and geologists. We will consider only the outer crust and the atmosphere. As the surface and the atmosphere above it gradually cooled, the formation of nitrides, and later of hydrides, sulphides and chlorides, occurred. ”

“ There is a realization of the instability of the earth’s crust, in spite of the solidarity of its component parts, but though the sudden shocks bring home this truth, it is not so readily grasped that day by day and hour by hour parts of the earth’s crust are slowly rising and others sinking, offering stern problems to the dwellers on the shores where these changes are most markedly taking place. ”

“ As to the crustal movement whose tendency is to spill the waters westward out of the Erie basin, we may observe that the earth's crust is most uneasy and its movements most uncertain. Nearly every place is going either up or down, few are in a state of actual quietude. ”

“ In the present state of our knowledge, we can explain such appearances only by supposing that the heated materials within the earth's crust poured out frequently, meeting little resistance,—that they then scattered and were precipitated in the ocean around, settling in successive strata at its bottom,—that through such strata the heated masses within continued to pour again and again, forming for themselves the chimney-like outlets above mentioned. ”

“ The common rocks of the crust are about two and a half times heavier than water, while the earth as a whole weighs five and six-tenths times as much as a globe of water of the same size. THE INTERIOR IS THEREFORE MUCH MORE HEAVY THAN THE CRUST. This may be caused in part by compression of the interior under the enormous weight of the crust, and in part also by an assortment of material, the heavier substances, such as the heavy metals, having gravitated towards the center. ”

“ At the conclusion of the Wealden period, the crust of our globe underwent another great change. The fresh-water rocks we have just been studying were probably submerged by some violent subterranean or subaquean agency, and upon a great part of them a new deposit was gradually formed. Foot by foot, and inch by inch, slowly accumulated those cretaceous particles (Lat. creta, chalk) which now constitute the chalk hills and cliffs of our own country, to say nothing of the extent of territory in Europe occupied by this well-known mineral. ”

“ Since the dawn of geological science, it has been evident that the crust on which we live must be supported on a plastic or partially liquid mass of heated rock, approximately uniform in quality under the whole of its area. ”

“ Another series of facts which serve to convince the geologist of the reality and potency of the forces ever at work within the earth's crust, and the way in which these have operated during past geological periods, is found in the disturbed condition of many of the stratified rock-masses of which it is composed. ”

“ The streams beneath the crust gradually wear away their channels leaving open spaces above them, which give out a hollow sound when one walks over them, and in them the rippling or gurgling of flowing water is to be heard more or less, beneath the crust. ”

“ So far as the formation of crust is concerned, it is doubtless due to the fact that the water in the soil holds in solution certain mineral matters, which it deposits at the point of evaporation, the collection of these finely divided matters serving to completely fill the spaces between the particles of soil at the surface,—pasting them together, as it were. ”

“ In the youth of our planet, the substances of the interior being still fluid, penetrated through the everywhere fissured crust of the globe, sometimes becoming solidified in the form of rocky veins or dykes of granular texture, and sometimes spreading out in broad sheets, and resembling superimposed strata. ”