Pallas informs us that he has found the granite not only changed
into porphyry, but also into the other alpine compositions. How an
argument for the originality of these mountains can be established upon
those facts, I am not a little at a loss to conceive.
The general mineralogical view of the Russian dominions, which we have,
in this treatise, may now be considered with regard to that distinction
made by naturalists, of primitive, secondary, and tertiary mountains, in
order to see how far the observations of this well informed naturalist
shall be found to confirm the theory of the earth which has been already
given, or not.
The Oural mountains form a very long chain, which makes the natural
division betwixt Europe and Asia, to the north of the Caspian. If in
this ridge, as a centre of elevation, and of mineral operations, we
shall find the greatest manifestation of the violent exertion of
subterraneous fire, or of consolidating and elevating operations; and if
we shall perceive a regular appearance of diminution in the violence or
magnitude of those operations, as the places gradually recede from
this centre of active force; we may find some explanation of those
appearances, without having recourse to conjectures which carry no
scientific meaning, and which are more calculated to confound our
acquired knowledge, than to form any valuable distinction of things.
Pages:
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327