Science from an easy chair : a second series / by Sir Ray Lankester.

  • Ray Lankester
Date:
[1915]
Catalogue details

Licence: In copyright

Credit: Science from an easy chair : a second series / by Sir Ray Lankester. Source: Wellcome Collection.

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    incredible. Close to one great precipice of orderly horizontal layers you see the whole series suddenly turned up at right angles, and the same strata which were horizontal have become perpendicular. But that is not the limit, for the upturned strata are seen actually to turn right over, and again become horizontal in a reversed order, the strata which were lowest becoming highest, and the highest lowest. The rock is rolled up just as a flat disc of Genoese pastry—consisting of alternate layers of jam and sponge-cake—is folded on itself to form a double thickness. The forces at work capable of treating the solid rocks, the foundations of the great mountains, in this way are gigantic beyond measurement. This folding of the earth’s crust is caused by the fact that the “ crust,” or skin of the earth, has ceased to cool, being warmed by the sun, and therefore does not shrink, whilst the great white-hot mass within (in comparison with which the twenty-mile-thick crust is a mere film) continually loses heat, and shrinks definitely in volume as its temperature sinks. The crust or jacket of stratified rock deposited by the action of the waters on the surface of the globe has been compelled—at whatever cost, so to speak to fit itself to the diminishing “ core ” on which it lies. Slowly, but steadily, this “ settlement ” has gone on, and is going on. The horizontal rock layers, being now too great in length and breadth, adjust themselves by buckling just as a too large, ill-fitting dress does— and the Alps, the Himalayas, and other great mountain ranges, are regions where this “ buckling ” process has for countless ages proceeded, slowly but surely. Probably the “ buckling ” has proceeded to a large extent without sudden movement, but with a lateral pressure of such power as ultimately to throw a crust of thousands of feet thickness into deep folds a mile or so in vertical measure¬ ment from crest to hollow, protruding from the general
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