408 Review of the Progress of 
certain directions, gradually dying out on either side, and sub- 
siding at the extremities. ave, however, here shown that 
the line of the Appalachian chain is the line of the greatest 
accumulation of sediments, and this great mountain barrier is 
due to original deposition of materials, and not to any subsequent 
press breaking up or disturbing the strata of which it is com- 
posed. 
the Alps, Pyrennees and Alleghanies, which are made up of 
aqueous sediments, has been imposed upon the world by the 
mountains, and later, in 1832, we find De Montlosier protesting 
against the elevation hypothesis of Von Buch, and maintaining 
that the great mountain chains of Europe are but the remnants 
of continental elevations which haye been cut away by denuda- 
tion, and that the foldings and inversions to be met with in the 
structure of mountains are to be looked upon only as local and 
accidental, 
In 1856, Mr. J. P. Lesley published alittle volume entitled Coal 
and is Topography, (12mo, pp. 224), in the second part of which 
he has in a few brilliant and profound chapters discussed the 
papeiples of topographical science with the pen of a master. 
ere he tells us that the mountain lies at the base of all topo- 
graphical geology. Continents are but congeries of mountains, 
or rather the latter are but fragments of continents, separated b 
valleys which represent the absence or removal of mountain 
land (p. 126); and again “ mountains terminate where the rocks 
thin out.” (p. 144. 
‘The arrangement of the sedimentary strata of which moun- 
tains are composed may be either horizontal, synclinal, anticlinal 
or vertical, but from the greater action of diluvial forces upon 
anticlinals in disturbed strata it results that great mountain 
