No. 50.] 
407 
Creek, five miles from Philipsburgh, we find the green sliale, not so 
highly fossiliferous, and with it thin courses of coarse-grained sand- 
stone, containing abundance of a large species of Delthyris. This 
fossil occurs in a rock of similar texture in many places of the same 
elevation, and may be found to constitute a definite point, or to mark 
the termination of some group ; certain it is that along this line we 
find scarcely any fossiliferous rocks above it. This sandstone, and the 
contained fossils, very much resembles that near the south line of the 
State, on the Tioga river, and again on Troup's creek, in Steuben ; 
and loose masses are found at intervals along nearly the same line from 
the Genesee river to the eastern limit of the District. In all cases 
where we approach the State line south, there is greater difiiculty in 
ascertaining the connexions between rocks. The ravines and water 
courses are not so deep, and the natural sections are not so well 
exposed. 
The next place south of Vandermark's creek, where locks are seen, 
is on Dike creek, near Wellsville, at an elevation of 60 or 70 feet 
above the Genesee, and between 1500 and 1600 feet above tide 
water. 
The rock at this place consists principally of grey sandstone, 
embracing a brick red or brownish mass six or eight inches thick. 
This is composed of sand, or rounded particles of quartz, with 
much argillaceous matter, splitting into laminae, half an inch or an inch 
in thickness, and is so highly impregnated with iron that it stains the 
hands nearly as much as the Oolitic ore of Wayne county, but is not, 
like that, unctious to the touch. It is considered by the inhabitants as 
a stratum of iron ore ; but its specific gravity proves the proportion of 
metal to be too small ever to repay working. Single joints of crinoidea 
occur in this and the grey rock below. On close inspection, the mate- 
rials of this mass appear to have been subjected to much wearing ac- 
tion, and many specimens exhibited numerous fragments of bones, 
apparently belonging to fish, and similar to those found in the red sand- 
stone on the Tioga.* 
This rock, examined here and several miles south, is succeeded by 
a mass consisting of greenish grey sandstone, often appearing as if 
deposited from opposing currents, and in all respects resembling that 
*See page 393. 
