Page:The Eurypterida of New York Volume 1.pdf/11

 engaged in acquiring these fossils and when the work was done the rock exposure was left with a vertical face, so that no further product is now available. In this eastern region of New York State the Salina formation is without salt deposits but the Otisville basin doubtless antedated those deposits in central New York and is assignable to an early part of the Salina stage.

Colony P, or the Pittsford pool, is embedded in a black shale formation which has never been exposed in any natural outcrops. As we have observed, the rock was first brought to light by excavations made in the deepening of the Erie canal in 1895 and the outcrops were soon after covered by the riprap construction of the canal lining and so remain. Extensive collections of material were made by Mr Clifton Sarle and these were subsequently increased by the work of Messrs D. D. Luther, H. C. Wardell and Fred. Braun. The opportunity of further acquisitions from this fauna rests with the future and depends on possible new excavations in the progress of public improvements.

Colony H, or the Herkimer pool, has been long exploited. It lies above the horizon of the salt and its localities are in the vicinity of Jerusalem Hill, Clayville, Sauquoit and Waterville. The most productive parts of the region have been the Wheelock and Schooley farms near Jerusalem Hill, though here as elsewhere actual outcrops of the waterlime are few. Experience has shown that the exploitation of the fresh rock does not afford eurypterids in satisfactory preservation, because of its blue gray character. Exposure not only reduces this to a light gray but aids the fissility of the rock and the broad, flat surfaces of the fossils also help to induce cleavage planes in the matrix. Exposure of a few years to the weather aids but little. The experiment was made of taking from the outcrop a good many cords of fresh rock which were left exposed for a period of five years but the result in the particulars referred to was wholly unsatisfactory. Therefore the supply of these fossils has come from weathered slabs distributed over this region. Miles of stone fences have been inspected and many rods of them taken down and rebuilt. Some of