Annual report of the Regents . orkstate are included under this head. As a whole, the group con-sists of interbedded shales and sandstones, the former prominenttoward the west, the latter becoming predominant to the shales vary in color, and are black, olive or green. The shalessometimes pass into shaly sandstones; these are often highly mica-ceous. The members of the group recognized by Prof. Hall, be-ginning at the top, are: 6 Sandstone and conglomerate 6 Old red sandstone 2 Black, slaty shale 3 Green shale with gray sandstones 4 Gray and olive shales and shaly sandstone1 Olive, sha
Annual report of the Regents . orkstate are included under this head. As a whole, the group con-sists of interbedded shales and sandstones, the former prominenttoward the west, the latter becoming predominant to the shales vary in color, and are black, olive or green. The shalessometimes pass into shaly sandstones; these are often highly mica-ceous. The members of the group recognized by Prof. Hall, be-ginning at the top, are: 6 Sandstone and conglomerate 6 Old red sandstone 2 Black, slaty shale 3 Green shale with gray sandstones 4 Gray and olive shales and shaly sandstone1 Olive, shaly sandstone Portage sandstone Of these members 2, 3 and 4 are the most important to clayworkers; the beds of shale exposed are often 20 or 30 feet in thick-ness and free from sandstone. ^ On the Genesee river the shale is often in thick beds of abright green color and scarcely interrupted by sandy layers \ Westward from the Genesee river there appears to be a con-stant augmentation in the quantity of the green shale, which is. a> i ^ op. CLAYS OF NEW YORK 837 often the predominating rock, though from weathering to an olive•color it does not always appear as distinctly . ^^ In the ravines in Chautauqua co., extending toward LakeErie, the shale still retains its green color . Jamestown, Chautauqua co. This sample of shale came fromthe hank of the Jamestown shale paving brick co. This was a rather gritty shale, which required ^ of water tomake a workable paste; plasticity, lean. The paste shrunk ,^ indrying, and an additional ^ in burning, making a total shrink-age of 12^. Air-dried briquettes made of this mud had an averagetensile strength of 16 pounds a square inch, and a maximum of 20pounds a square inch. This low tensile strength was due to thesilicious character of the shale which, however, permitted rapiddrying. Incipient fusion occurred at cone .04, vitrification at cone .01and viscosity at cone 3. The clay burns to a deep red and densebody. A sample collect
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