Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1882 edition. Excerpt: ...will find that not only have the rocks of.the earth's crust been folded in this equable and gentle way; but that they present proofs of much more intense movement. These may be looked for in the vicinity of faults, as has already been pointed out. Sudden and violent crumpling in the midst of comparatively undisturbed strata may be regarded as prima facie indicative of the proximity of some dislocation. It will not however of itself be sufficient to prove the existence of a fault, for unexpected local twists and severe plication sometimes occur where, though the rocks must have been subjected to intense lateral compression, they have not actually been fractured. On a small scale the most tumultuous contortion of soft strata may often be seen as the result of a landslip. In Fig. 43, for example, a set of dark shales lying under a thick sandstone have been crushed up by slips of the heavy over-lying rock, yet the ruin has been so well concealed by vegetation that a careless observer might suppose the lower twisted beds to be much older than, and unconformably covered by, the upper horizontal strata. There occur wide tracts of country where the underlying rocks have been so violently disturbed, that for miles they seem to be standing on end. In such cases it is usual to find some one prevalent direction of strike along which the vertical or highly inclined beds range themselves. And a careful examination will generally disclose Fig. 44.--Section of what at the surface might be mistaken for a continuous highly inclined series of strata, shown to consist of numerous anticlinal and synclinal folds. Gneissose rocks. Lock Quoich, Invernesshire. proofs that the strata really consist of many rapid folds, the same beds being repeated again and again....
