EVOLUTION OF THE EARTH'S FEATURES. — MOUNTAIN-MAKING. 749 



sedimentary beds in the trough, the Appalachians being referred to as an example. 

 But he made the subsidence a consequence of the sedimentary accumulation, and not 

 the accumulation a consequence of the subsidence, throwing aside lateral pressure al- 

 together. The earth's crust would have had to yield like a film of rubber, to have 

 sunk a foot for every added foot of accumulations over its surface; and mountains 

 would have had no standing-place. 



2. The bottom of the Geosynclinal weakened by the Heat rising into 

 it from below. — As planes of equal temperature within the earth 

 have a nearly uniform distance from the surface, the accumulation of 

 sedimentary beds in the sinking trough would occasion, as Herschel 

 long since urged, the corresponding rising of heat from below, so that, 

 with 40,000 feet of such accumulations, a given isothermal plane 

 would have been raised 40,000 feet. Under such an accession of heat, 

 the bottom of the trough would be greatly weakened, if not partly 

 melted off. If the lower surface of the crust had dipped down this 

 much into the plastic layer that was beneath it, it would have been 

 actually melted off. 



3. The Heat in the lower part of the trough increased by the Trans 

 formation of Motion into Heat. — The heat from the transformation 

 of the motion of the crust would have been of feeble amount, if the 

 motion were extremely slow and regular. But, with fractures, shov- 

 ings, and crushing accompanying it, the heat from the rise of the iso- 

 geothermal would have been much reenforced. 



4. The weakened trough yields before the Pressure. — The lateral 

 pressure, acting against a trough thus weakened, would end, as Hunt 

 has observed, in causing a collapse, that is, a catastrophic break of 

 the trough below, and a pressing together of the stratified beds within 

 it. And with this break the shaping of the mountain would begin. 



5. Character of the Mountain thus made. — Under such circum- 

 stances, the stratified rocks would be folded, profoundly broken, 

 shoved along fractures, and pressed into a narrower space than they 

 occupied before ; and thus they would become raised, as argued by 

 Le Conte, above their former level, so that a mountain-range would 

 be the result, even without any actual uplift of the crust beneath. 

 The„crust beneath was that of the geosynclinal ; and lateral pressure, 

 however powerful, could not possibly have raised at the time the 

 downward flexed crust. 



6. The finished Mountain Range a Synclinorium. — Such a moun- 

 tain-range, begun in a geosynclinal, and ending in a catastrophe of • 

 displacement and upturning, is, as named by the author, a synclinorium, 

 it owing its origin to the progress of a geosynclinal. (The word is 

 from the Greek for synclinal, and opos, mountain.) Although at first 

 consisting of a series of parallel folds of strata, with the anticlinals 

 greatly broken, — the anticlinals, perhaps two, or three, or more miles 



