. Bulletin of the Geological Society of America. Geology. 334 M. JEFFERSON—LATERAL EROSION ON MICHIGAN RlVERS These bare strips, or "scaurs," as they are called in Scotland, lie at points where the meandering stream is now close to the valley wall, undermining it and causing it to cave and slip. Such points of contact between stream and bounding valley bluff may often be seen alternating to right and left in a view down valley, the up-valley aspect being wholly of grassy slopes. This is because the downstream migration of meanders causes a constant attack on the up-valley side of ree
. Bulletin of the Geological Society of America. Geology. 334 M. JEFFERSON—LATERAL EROSION ON MICHIGAN RlVERS These bare strips, or "scaurs," as they are called in Scotland, lie at points where the meandering stream is now close to the valley wall, undermining it and causing it to cave and slip. Such points of contact between stream and bounding valley bluff may often be seen alternating to right and left in a view down valley, the up-valley aspect being wholly of grassy slopes. This is because the downstream migration of meanders causes a constant attack on the up-valley side of reentrant cusps, which are therefore the especial site of scaur, while the downstream side of the same reentrant watches the stream that once bathed its foot draw steadily away—a process admirably described by Davis. Valleys like this are typical of Michigan south of the Grand-Saginaw valley. Results of the. Figure 1.—Scaur on the right Bank of the Lower Rouge. The river carries off creeping waste as fast as it falls, and the banli retreats. uniform softness of the material in which they are cut are the rapidity with which they are made, the tolerable grade of their course, and the youthful slopes by which their flood-plains are everywhere bounded. The topographic sheets of the U. S. Geological Survey are not usually accurate enough or detailed enough to show the character of these valleys or even the meandering of the streams that carve them, and the topog- raphers have not recognized the existence of these forms. It is appro- priate to their slight recognition that what I have called scallops in the bluff have no accepted name among writers on the siibject, The sheet. 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 Geological Society of America. [New York : The Society]
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