g5 On the Declivities of Mountains. 



water moved in two general directions, at right angles with 

 each other; the one from eaft to weft, which needs not to 

 be proved, being the courfe of tides which ftill continue, 

 but were in that ocean neceffarily itronger and higher than 

 at prefenl ; the other from north to fputh ; the water tending 

 to thofe vaft abyffes then formed in the vicinity of the South 

 Pole, as fhown in my former effays, Before either motion 

 could be propagated, a confiderable time mull have elapfed. 



Now the primeval mountains formed at the commence- 

 ment of the firft sera, and before this double direction of the 

 waters took place, mud have oppofed a confiderable obftacle 

 to the motion of that fluid in the fenfe that croffed that of 

 the direction of thefe mountains. Thus, the mountains that 

 ftretch from north to fouth muff, have oppofed the motion of 

 the waters from eaft to weft ; this oppofition, diminifhing the 

 motion of that fluid, difpofed it to fuffer the earthy particles, 

 with which in thofe early periods it muft have been impreg- 

 nated, to cryftallife or be depofiled on thefc eaftern flanks, 

 and particularly on thofe of the higheft mountains, for over 

 the lower it could eafily pafs : thefe depofitions, being incef- 

 fantly repeated at heights gradually diminifliing as the level 

 of the waters gradually lowered, muft have rendered the 

 eaftern declivities, or defcent, gentle, gradual, and moderate ; 

 while the weftern fides, receiving no fuch acceffions fronx 

 depofitions, muft have remained fteep and craggy. 



Again, the primxval mountains that run from eaft to weft, 

 by oppofitig a fimilar rciiftaqce to the courfe of the watery 

 from north to fouth, muft have occafioned fimilar depofitions 

 on the northern fides of thefe mountains, againft which thefe 

 waters impinged, and thus fmoothed them. 



Where mountains interfeft each other in an oblique di- 

 rection, the north-eaft fide of one range being contiguous to 

 the for.th-weft flanks of another range, there the afflux of 

 adventitious particles on the north-eaft fide of the one muft 

 have frequently extended to the fouth-weft fide of the other, 

 particularly if that afflux were ttrong and copious : thus the 

 jBrqgebirge of Saxony, which run from weft to eaft, have 

 their north-eaft fides contiguous to the fouth-weft fide of the 

 Riejfeng$bwg(t that fepajate Silefia from Bohemia; and henc e 

 7 thefe 



