. Bulletin of the Geological Society of America. Geology. BURIED STRANDS OF LOP 373 stream after it had carved a channel in the soft clays numbered 1 to 4. Elsewhere along the sides of the mod- ern gully where the section shown in figure 13 is exposed, the whole of the cross-section of the old channel can be seen. The channel is cut in clay and sand, and forms a typical fossil stream bed of gravel several hundred feet wide. Figure 13 shows how it hap- pened that the old stream of figure 12 could cut so deep a channel. A-B seems to be a battered lacustrine bluff, cut by the lake when the water
. Bulletin of the Geological Society of America. Geology. BURIED STRANDS OF LOP 373 stream after it had carved a channel in the soft clays numbered 1 to 4. Elsewhere along the sides of the mod- ern gully where the section shown in figure 13 is exposed, the whole of the cross-section of the old channel can be seen. The channel is cut in clay and sand, and forms a typical fossil stream bed of gravel several hundred feet wide. Figure 13 shows how it hap- pened that the old stream of figure 12 could cut so deep a channel. A-B seems to be a battered lacustrine bluff, cut by the lake when the water stood some 50 or 60 feet above the present level. The lake stood at this height long enough to cut a bluff resembling that of plate 33, figure 3. Later the water rose above the bluff at various times and the overlying strata were deposited. It is impossible to assign a date to the fossil bluff of figure 13. It was certainly formed before the time of the 115-foot strand and probably before that of the 300- and 600-foot strands. As appears in figure 5, the strata above the unconformity consist of ivro de- l)osits of semi-lacustrine ami very saline red clay separated by -41 feet of sub- aerial deposits belonging to an unmis- takable interlacustral epoch. The upper layer of saline deposits lies well above the 115-foot strand, and clearly ante- dates it. The lower layer of saline de- posits is, of course, still older. It may be that the two were formed during the 300- and 600-foot epochs of lake ex- pansion, although the red color seems to he against this. In the present ab-. 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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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
