In this
note I have collected all the certain information I could find regarding the
greatest absolute and relative depths of mines and borings. In descending
eastward from Jerusalem toward the Dead Sea, a view presents itself to the
eye, which, according to our present hypsometrical knowledge of the surface
of our planet, is unrivaled in any country; as we approach the open ravine
through which the Jordan takes its course, we tread, with the open sky above
us, on rocks which, according to the barometric measurements of Berton and
Russegger are 1385 feet below the level of the Mediterranean. (Humboldt,
'Asie Centrale', th. ii., p. 323.)
The crystalline masses that have been erupted from active volcanoes, and are
generally similar to the rocks on the upper surface, have come from depths
which, although not accurately determined, must certainly be sixty times
greater than those to which human labor has been enabled to penetrate. We
are able to give in numbers the depth of the shaft where the strata of coal,
after penetrating a certain way, rise again at a distance that admits of
being accurately defined by measurements. These dips show that the
carboniferous strata, together with the fossil organic remains which they
contain, must lie, as, for instance, in Belgium, more than five or six
thousand feet* below the present level
p 160
of the sea, and that the calcareous and the curved strata of the Devonian
basin penetrate twice that depth.
Pages:
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332