.. Key to the upper Devonian of southern New York; designed for teachers and students in secondary schools . Fig. J. and Long.), the one approximately as the area appeared in De-vonian times, the other as it appears to-day—showing especially the distribution of the Portage and Chemung groups of southernNew York. Into the Embayment of the sea flowed large rivers,and brought the sand, mud and slime among which lived theshells hereinafter figured. It is this vast accumulation of sedi-mentation that has subsequently been raised above sea-level andstill later carved by flowing waters that makes the
.. Key to the upper Devonian of southern New York; designed for teachers and students in secondary schools . Fig. J. and Long.), the one approximately as the area appeared in De-vonian times, the other as it appears to-day—showing especially the distribution of the Portage and Chemung groups of southernNew York. Into the Embayment of the sea flowed large rivers,and brought the sand, mud and slime among which lived theshells hereinafter figured. It is this vast accumulation of sedi-mentation that has subsequently been raised above sea-level andstill later carved by flowing waters that makes the beautifully di-versified region of southern New York. The Portage material was deposited first, hence underlies,passes under, the Chemung. Beneath the Portage in turn areMiddle Devonian, Hamilton beds, cropping out across the statenorth of the Portage. They passed through similar stagesof formation to those of the Upper Devonian beds, though in asomewhat more remote period of Ij|j!,|| Area when Portage rocks are near the beneath soil. Area where Chemung rocks are near the surface,just beneath soil. FiZ- 4- PART 11. THE UPPER DEVONIAN OF SOUTHERN NEW YORK. Subdivisions. The Portage Group.—Many local names have been appliedto the rocks of this group on account of their varied appearanceat different localities. At base, from Chenango river westwardto Lake Erie, is the Genesee shale, a thin-bedded, fragile, shah-mass, varying in thickness from a few feet only in the east to 125feet in central New York. Its fossils are few and generallysmall, and mainly confined to the basal and upper layers. (SeeFigs. 1-9, ) Fish remains are reported from these shales onthe shore of Lake Brie and at a few other localities. Above, are the Sherburne shales and sandstones in the east,the Lower Portage shaly sandstones of Cayuga lake section, thelower Cashaqna and Gardeau shales (Naples beds) and sandstonesof the Genesee section and west to Lake Erie. Thickness
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Keywords: ., boo, bookcentury1800, booksubjectgeology, booksubjectpaleontology
