DEVONIAN AND CARBONIFEROUS IN NEW YORK 525 



over the Olean and the eastern part of the Salamanca sheet and was the key rock 

 for determining the stratigraphy of much of this region. It marks the first promi- 

 nent change in sedimentary conditions in the region and is regarded as a lentil 

 marking the base of, and belonging to, the Cattaraugus formation. 



Shales and saiidstones.— The Wolf Creek conglomerate was succeeded by bright red 

 shales interbedded with green or bluish shales and fine grained, greenish gray, thin 

 bedded, micaceous sandstones that together extend upward through an average in- 

 terval of 300 to 350 feet. This portion of the stratigraphic column, in which bright 

 red shales occur along with the Wolf Creek conglomerate lentil, is regarded as a 

 formation, and to it the name Cattaraugus is given. Two other conglomerate 

 lentils, the Salamanca and the Kilbuck, occur in it. 



The bright red argillaceous shales of the Cattaraugus are entirely different from 

 the dark brick red or purplish shales of the Chemung. No bright red shales occur 

 in this region below Wolf creek, but they soon appear above it. They are usually 

 fine grained and argillaceous, though in places they become sandy and may locally 

 pass, especially southeastward, into thin red argillaceous sandstone. It is not cer- 

 tain that the individual beds of red shale are persistent or hold their thickness for 

 more than short distances, but it is certain that westward in.the Salamanca region 

 and south westward in Warren county, Pennsylvania, the beds of red shale tend to 

 disappear. Their disappearance appears to be due to their grading over westward 

 and south westward into deposits of other than red color. The stratigraphic equiva. 

 lents of the red shales are, as a rule, present to the westward, but their color has 

 changed to olive green, blue, or drab. There are, however, evidences of erosion 

 at this horizon, as will be seen later, but this erosion will not account for the dis- 

 appearance of the reds. 



The lighter colored shales interbedded with the red ones vary from fine blue 

 mud shales to light or dark green sandy ones. Along with the shales are greenish 

 gray, medium to fine grained, soft, arkosic sandstones, often thin or cross-bedded, 

 and with their parting planes flecked with mica particles. The individual beds of 

 sandstone do not seem, as a rule, to be persistent, except for short distances. 



Fossils. — After the deposition of the Wolf Creek conglomerate, which contains 

 in its upper portion especially a marine fauna, fossils rapidly disappear, and the 

 red and green shales and the fine micaceous sandstones generally yield but few or, 

 for considerable intervals, no forms. Conditions as a whole were evidently un- 

 favorable to animal life w^hile these beds were being deposited. The Salamanca 

 and Kilbuck conglomerate lentils are, however, fossil iferous. 



Salamanca conglomerate lentil. — The Salamanca lentil occurs at about the middle 

 of the Cattaraugus formation. It thins out and disappears to the eastward. It 

 occurs in the south western part of the Olean area as a hard gray sandstone 10 to 15 

 feet thick, which becomes coarser and thicker westward and passes into a massive 

 conglomerate on the Salamanca quadrangle. The sandstone phase is well exposed 

 in a number of small quarries on mount Herman just south of Olean, where it is 

 locally known as the Mount Herman sandstone. 



Its massive conglomeratic character is best developed in the Salamanca region, 

 and may be well seen up Limestone and Irish brooks, along Red House creek, at 

 Salamanca " rock city," and at numerous other places. 



In thickness, coarseness, and massiveness it is also variable, though not as mark- 

 edly or abruptly so as the Wolf Creek. In its more massive phase it is often 

 strongly cross-bedded, and in places is separated into two benches, with a shale 



