. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. Il8 NEW YORK STATE MUSEUM ably on the former, this unconformity being emphasized by the absence of all Lower Devonic strata in this region, with the excep- tion of thin lenses of sandstone which may be correlated with the Oriskany. The upper surface of the Manlius limestone is knotty and concretionary, producing minor irregularities, but in addition to these there are well marked traces of the erosion of these strata, prior to the deposition of the overlying beds. These traces are of the nature of channels and irr
. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. Il8 NEW YORK STATE MUSEUM ably on the former, this unconformity being emphasized by the absence of all Lower Devonic strata in this region, with the excep- tion of thin lenses of sandstone which may be correlated with the Oriskany. The upper surface of the Manlius limestone is knotty and concretionary, producing minor irregularities, but in addition to these there are well marked traces of the erosion of these strata, prior to the deposition of the overlying beds. These traces are of the nature of channels and irregular truncations of the strata, the former in some cases assuming considerable importance. (Fig. 21-23) In the east wall of the quarry, not far from the stamp mill, the surface of the Manlius limestone is strongly ex- FigA21 Unconformable contact between Manlius cavated, the excavation being and Onondaga limestones, Buffalo cement quarry. > » mainly filled by beds of the Onondaga limestone. Be- tween the two limestones oc- curs a mass of shale and conglomerate having a total thickness, in the central por- tion, of something over a foot. The lower 6 or 8 inches are a lime- stone conglomerate, the pebbles of which are fragments of the underlying limestones. These pebbles are flat, but well rounded on the margins, showing evidence of protracted wear. They are firmly embedded in a matrix of indurated quartz sand, which surrounds them and fills in all the interstices. This bed thins out toward the sides of the channel. On the con- glomerate lie about 6 inches of shale and shaly limestone, and these are succeeded by the Onondaga limestone. The width of the channel, which is clearly an erosion channel, is about 18 feet, and its depth is about 3! feet. (Fig. 23) From the point where this channel is seen, the contact can be traced continuously for a thousand feet or more eastward, along the quarry wall. It frequently shows a thin shaly bed, often containing quartz grains, lying be
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