120 



NEW YORK STATE MUSEUM 



diatoms were also found : Navicula Gruendleri, A. S. ; Navicula 

 permagna, Edw. (fragments) ; Melosira granulata (Ehr.) Ralfs ; 

 Nitzshia granulata, Grun. All fresh water species. At Croton 

 Landing a number of impressions were found in the blue clay 

 and these on being submitted to Prof. Hall were pronounced to 

 be worm tracks. Mather in his report* mentions the finding of 

 leaves in the clay beds back of the medical college at Albany, 

 and states that they resemble those of an aquatic plant. 



The Clays of the Champlain Valleyf 



The clays of the Champlain valley are estuary formations and 

 of the same age as the Hudson Iliver clays. They underlie ter- 

 races along the lake which have been elevated to a height of 393 

 feet above sea level. These terraces may be traced almost 

 continuously from Whitehall, at the head of Lake Champlain, to 

 the northern end of the lake and beyond it, but on account of the 

 extensive erosion which has taken place they are usually narrow, 

 and it is only at sheltered points like Port Kent and Beauport 

 that they become specially prominent. The section involved is 

 yellowish brown sand, yellowish brown clay and stiff blue clay, 

 the latter being rather calcareous. The upper clay is somewhat 

 siliceous, and its coloring is due to the weathering of the lower 

 layer. This formation has a thickness of about 15 feet, but 

 sometimes, as at Burlington, it reaches a thickness of 100 feet. 

 Isolated bowlders are occasionally found in the clays, and are 

 considered by Emmons to have been dropped there by icebergs. 

 The clays are usually horizontally stratified, and contortions of 

 the layers are extremely rare. Numerous fossils have been found 

 in the overlying sands, among them being Saxicava rugosa and 

 Tellina groenlandica, which are very common ; Tritonium 

 anglicum, Tritonium for nicatum, Mytilus edulis, Pecten island- 

 cus, My a truncata, M. arenaria, Nucula jportlandica • the skeleton 

 of a whale has also been found in these deposits.** 



Openings have been made in them for the purpose of obtaining 

 brick clays at Plattsburg and a few other localities, but owing to 

 the lateness of the season when I visited them information was 

 hard to obtain. 



* Geol 1st, Dist. N. Y., p. 123. 



tCompiled largely from Emmons Report, Qeol. N. Y. 2nd Dist. 



** The writer has found one spacies of diatom belonging to the genus Dixtoma in the clay from 

 Plattsburg. 



