PLEISTOCENE CLAYS. 127 



"The hypothesis that the water which covered this area was a 

 lake, rather than a bay, is worthy of consideration, though it is, 

 on the whole, less satisfactory The moraine and other drift de- 

 posits may have blocked the southern outlet of this region to the 

 height of 25 or 30 feet, between New Jersey and Staten Island. 

 If a similar dam obstructed Kill van Kull, or the Narrows and 

 East river, a lake would have come inlto existence in the tract 

 where the clay is. As the outlet was cut down, the lake was 

 drained. But even on this hypothesis, differential movement of 

 the surface must be supposed, for the surface of the clay is higher 

 to the north than to> the south. 



"It may here be added that there is abundant evidence of a 

 late submergence, at least to the extent of 40 feet, at various 

 points about the coast of southern New Jersey. The date of this 

 submergence was not earlier than the close of the last Glacial 

 epoch. 



"The clay of the Hackensack valley is everywhere covered by 

 sand, generally 8 to 15 feet in depth. At some points the surface 

 of the clay below the sand is leached and oxidized. It is, in most 

 places, not possible to say whether this leaching and oxidation is 

 the result of exposure before the deposition of the sand, or 

 whether it has taken place beneath the sand. The latter would 

 be somewhat out of keeping with the extent to which the drift 

 so far beneath the surface has generally been altered since its 

 deposition. 



"At two points specific evidence on this point has been ob- 

 tained. In 1893 one of the clay pits below Hackensack showed 

 the following section : 



"(5) 8 feet of fine, stratified sand, containing a few gneiss 

 bowlders. 



"(4) Stratified sand, 2 feet in depth, overlain by a few inches 

 of blue clay containing fragments o<f leaves and woody stems. 



"(3) 1 foot of black soil. 



"(2) 6 feet of laminated clay, containing an occasional 

 bowlder, calcareous up to within a foot of its upper limit. 



"(1) Till, seen in the bottom of the pit on its west side. 



"The old soil (3) was not far from sea level. A similar sec- 

 tion, so far as the old soil was concerned, was seen by Mr. Peet, 



