The international geography . s left dry and relatively barren. Thesefeatures are so characteristic of the Karst district of the Adriatic coastthat the name karst phenomena has been applied to them (see Fig. 156). Themore compact rocks weather differently according to their texture andarrangement. Thus a coarsely crystalline granite decomposes into clay andsand along the lines of cracks, and in the process assumes the bold serratedoutlines familiar to the observer in all granite mountains ; but the closergrained basalt is much more durable. A dyke or sheet of igneous rockembedded in sedimentar
The international geography . s left dry and relatively barren. Thesefeatures are so characteristic of the Karst district of the Adriatic coastthat the name karst phenomena has been applied to them (see Fig. 156). Themore compact rocks weather differently according to their texture andarrangement. Thus a coarsely crystalline granite decomposes into clay andsand along the lines of cracks, and in the process assumes the bold serratedoutlines familiar to the observer in all granite mountains ; but the closergrained basalt is much more durable. A dyke or sheet of igneous rockembedded in sedimentary strata stands out sharply when the softer rockshave been weathered away. Again, the forms of a region where the stratalie horizontally like the Grand Can3^on district of the United States, differfrom those of one where the rock sheets dip regularly in one dip-slope weathers more slowly than the steeper edge or escarpment,which runs along the direction of the strike (Fig. 30). This is seen best on Land Forms 55. Fig. 30.—Diagram illustrating dip, strike,dip-slope, and escarpment. sea-coasts and river-valleys where the character of the cliffs carved out bythe waves or current varies in accordance with the structure as well as theresisting power of the rocks. Ex-cept in the newest volcanic for-mations the surface of all exposedrocks has been greatly altered .byweathering, and so far as theirscenery is concerned the upraisingof the land has served mainly toguide the ceaseless action of thetools of erosion. The result ofprolonged erosion on an ancientplateau is to cut it up into detachedmasses of mountainous magnitude, which on account of their origin havebeen called relict-mountains, or mountains of circumdenudation. River Work—Destructive.—As the streamlets flow down any slopeto meet and form a larger stream they begin to wear a channel for them-selves, which gradually cuts deeper and deeper into the ground, the sidesbeing steadily widened by weathering as th
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectgeography, bookyear19
