Clarke — Oneonta, Ithaca and Portage (tropin. 



47 



present the roughness of alluvial scratches, but appear to have been made before the rock was entirely 

 indurated, or else they have been modified by the deposition of shale which succeeded. In this instance 

 I have not been able to ascertain the direction of the current, though it was probably from the north, 

 and like all other currents in the ancieut seas, took the direction from the greatest elevation to the 

 lowest point. 



"In some localities the sandstone is replaced by a kind of sandy shale, being a mixture of sand 

 and clay, and the whole is rippled, the markings affecting each thin layer, and showing that it was 

 deposited from water in motion, which might transport from different directions the two materials of 

 the rock. This group appears to have been deposited from an ocean alternately at rest and disturbed. 

 Thick masses of sandy shale occur, bearing ripple marks through their whole depth; these are succeeded 

 by others of variable thickness, without ripple marks, and having the faces smooth and plain. 

 Numerous alternations of this kind have been noticed through many hundred feet. Fossils never 

 accompany the rippled layers, but are invariably found with the smooth. The materials of the two 

 differ very slightly in mineral composition, the rippled ones being more sandy. The absence of fossils 

 in the latter may be explained by supposing the unquiet state of water during the deposition of the 

 rippled shale to have been unfavorable to the development of organic life. So far as I have observed 

 in this and other localities, the greater accumulation of fossils is always accompanied by fewer ripple 

 marks. 



"The changeful state of our planet at that period may have occasioned numerous risings and 

 siukiugs of the crust, some portions of which may have been disturbed oftener than others, one under- 

 going the oscillatory movement while another was at rest. This may be considered proved from the 

 fact that undulations are exhibited in some localities, while a distance of a few miles shows a plane and 

 undisturbed surface. Thus the undulations of the rocks on Seneca lake have not been communicated 

 to those on the western shore of Crooked lake, although the latter are part of the same mass, separated 

 only by a distance of ten or twelve miles. The valley of Crooked lake could have had no influence in 

 interrupting the motive force, as probably at that time it was not excavated ; and farther south we find 

 other undulations of which the counterparts are exhibited on each side of the valley. 



"These uplifting movements would form bays or protect some portions of the sea where animals 

 might exist in great numbers, while every other part for miles in extent were too unquiet for the 

 development or preservation of animal life. 



"In numerous localities of these rocks the edges of strata, when exposed in ravines and other 

 places, are found covered with crystals of sulphate of lime. This circumstance is by no means universal 

 among the shales below, although observed in some localities, while in the present group there are few 

 exceptions. Pyrites in minute particles are everywhere disseminated, decomposing on exposure and 

 hastening the destruction of the rocks, while the sulphuric acid combines with the minute proportion 

 of lime which they contain, exhibiting the crystals along the edges. Wherever larger masses of pyrites 

 occur we find a proportionate increase in the quantity of sulphate of lime. Similar conditions in some 

 of the limestones below have produced a mass of gypsum, fiding the cavity previously occupied by the 

 pyrites; and analogous circumstances, varying in extent and effect, may have formed the va c c 

 gypsum beds of the sam». series, extending throughout the whole of western New York. The latter, 

 however, could only have occurred before the entire induration of the surrounding rocks. 



"CHEMUNG COUNTY. 



"In this county the group last described forms the surface rocks of the northern towns, and in the 

 ravines and valleys extends south to the southern line of the towns of Veteran and Catliu. The rocks 

 here retain most of their essential characteristics, but fossil shells are exceedingly rare, aud in many 

 localities entirely wanting. The peculiar fucoidal markings are every where preserved in the thin layers 

 of sandstone. The rocks of this group are well developed in Gulf creek, near Jefferson, at the head of 

 Seneca lake, and at many points south on the west branch of the valley aud the ravines coming into it. 



"From Jefferson to Millport the rocks dip south, exhibiting throughout continued alternations of 

 shale and sandstone, and towards the upper part the compact shale is covered with fragments of a 

 Fucoid, different from those below, and appearing only in curved fragments. 



" In the vicinity of Millport and farther south the sandstone layers attain a thickness of a foot or 

 more, and are quarried for works on the canal aud various other purposes, and at Pine valley the sandy 

 layers of the rocks are quarried in tsvo places. Mr. Sexton, the owner of the last, informs me that the 



