. Elementary physical geography . ated, and we may then havea narrow gorge cut in the center of a broad valley. After along period of denudation the uplift gives new powers to the stream, and itthen cuts a nar-row valley (). Such anuplift may affectgreat areas; andin the rivers thusrevived, waterfallsagain begin to develop, and nearly all of the appearancesof youth may return. Nearly every stream system showssome sign of this kind of rejuvenation, which has affected itsrecent development. If this elevation happens near the sea-coast, a part of the ocean bottom is raised to the condition
. Elementary physical geography . ated, and we may then havea narrow gorge cut in the center of a broad valley. After along period of denudation the uplift gives new powers to the stream, and itthen cuts a nar-row valley (). Such anuplift may affectgreat areas; andin the rivers thusrevived, waterfallsagain begin to develop, and nearly all of the appearancesof youth may return. Nearly every stream system showssome sign of this kind of rejuvenation, which has affected itsrecent development. If this elevation happens near the sea-coast, a part of the ocean bottom is raised to the conditionof dry land, and the streams of the old mainland extendacross it ; and perhaps by this means separate streams maybe united to form one system. Depression of the land would rob streams of some of theirforce by decreasing their elevation, and hence their the coast, the lowering of the land causes the oceanto extend up the valleys, drowning parts of the streams, andtransforming their mouths to estuaries or straits, while. Fig. showing the result of an elevation, whichcaused the inner canon of the Colorado to he cut be-tween the older walls of the outer and broader valley. RIVER VALLEYS. 277
Size: 3095px × 807px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthortarrralphsralphstockm, bookcentury1900, bookdecade1900
