. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 156 bulletin: museum of comparative zoology. aatch range. This may, as usual, be best demonstrated by consideration of the progress of wave work in an ideal case. If the surface of a sea or lake should rise on a ravined mountain front, so as to gain an irregular shore line, abcd, Figure 12, the promon- tories might in time be cut back to the straight shore line dfh, over which the spurs would then terminate in triangular cliff-facets, dkf, flh. But in such a case, the valleys should not remain narrow-mouthed
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 156 bulletin: museum of comparative zoology. aatch range. This may, as usual, be best demonstrated by consideration of the progress of wave work in an ideal case. If the surface of a sea or lake should rise on a ravined mountain front, so as to gain an irregular shore line, abcd, Figure 12, the promon- tories might in time be cut back to the straight shore line dfh, over which the spurs would then terminate in triangular cliff-facets, dkf, flh. But in such a case, the valleys should not remain narrow-mouthed during the progress of the wave work, but should widen somewhat and allow the streams to develop flood plains on which they could wander a little; and after the lake waters had disappeared, the facets should look out. Figure 12. Diagram of spurs cut by waves: ABCD, initial shore-line at time of submergence; DKF, cliff facet cut back in spur DEF; FGH, spur platform fronting its cliff facet FLH, after withdrawal of lake waters. upon triangular rock platforms, fgh, systematically related in form and area to the facets. As a matter of fact the triangular rock-platforms and the widened valley mouths are wanting in every case that came under my notice. It cannot be supposed that the mountain front was cut back by waves at so low a level that the wave-cut platform is now concealed by mountain waste ; for in that case the narrow ravines should also have been cut down to the same low level, instead of opening, as they so often do, rock-floored on the mountain flank, and allowing the streams to con- tinue their descent on gravel fans that rise at the apex distinctly above the intermont plain. One of the best localities for the illustration of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum
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Keywords: ., bookauthorha, bookcentury1800, bookdecade1860, booksubjectzoology
