568 PROCEEDINGS OF THE ACADEMY OF [1896. 



The view that the Fish-house clay is of Pleistocene age is materially 

 strengthened by the discovery therein of several horse teeth by Mr. 

 Lewis Woolman, and by the recognition of the identity of at least a 

 portion of the Umonida with living species, a subject referred to 

 below. 



The fossils occur only in a layer of black clay, which is used for 

 brick and tile making. This deposit is capped by a layer of coarse 

 sand. Under the black clay is a much thinner stratum of yellow 

 or reddish clay, containing considerable sand and deeply stained 

 with iron oxide. Below this stratum, which is about two feet thick 

 where observed, there is coarse gravelly sand, which forms the foun- 

 dation of the superimposed clays. This sand deposit is of consider- 

 able thickness, and the various sections exposed show it to be dis- 

 ___^____.:^_^r:;_r2^^^;^;r:2 tluctly stratified, the strata being obliquely 

 \UM7^'^&(0A^'H.i^^u-'% laminated, as shown in the annexed dia- 

 %^0M^'''''^^^''''-^^ gram. The character of these strata is 



^l^s^r- ;,.;;;*^j^,,e A^ completely that of arenaceous deposits in 



jj^ .,: ■^:..^.■J■;'•■^v:^^:■x''^^■>^ river-beds. So far as I know, such a 

 ...v^i.,-.-:-.=--.---"'<^-"-'-» '^^••'^•- disposition of the materials is not pro- 



^^^- 1- duced by any other means. No such 



Obliquely laminated strata. . .-a 4.- i i r i • t- 



^ ■^ stratincation and oblique lammation is 



to be seen in the coarse sand at the summit of the clays. This 

 difference indicates a diverse origin for the two deposits. In the 

 opinion of the writer, the peculiarities of the Fish-house clays may 

 be explained by the supposition that the deposit has been purely a 

 result of river-action. The phenomena are exactly paralleled by 

 processes now in progress in the rivers of the Mississippi system, 

 where similar deposits containing a similar fauna may be seen in 

 every stage of formation. 



Upon this theory the sands underlying the red clay were de- 

 posited in a former Delaware River bed, the river at that time flow- 

 ing in a direction practically parallel to its present course, as shown 

 by the direction of the oblique lamination of the strata. A change 

 in the river's course, such as cutting across the neck of an " ox-bow," 

 or some similar shifting, left the former bed at this point a lagoon, 

 similar to the so-called " sloughs " of the Mississippi River. A la- 

 goon of this nature, while it quickly becomes dammed at the up- 

 stream end, for a time receives a portion of the current in time of 

 high water. In the case under consideration, the layer of red, more 

 or less arenaceous, clay was probably deposited during this period of 



