GEOLOGY AND GEOGRAPHY OF CLAY DEPOSITS 



129 



The occurrence of these diatoms is a matter of great interest. 



While diatoms are abundant in the Tertiary, their only known 

 occurrence in the Cretaceous, is the chalk* which is upper 

 Cretaceous. This being the case, their occurrence at Northport 

 extends the known geological range of diatoms. 



At Fresh Pond the clay crops out along the shore for distance 

 of half a mile. It is brownish and red in color, the red being more 

 sandy. Sand and gravel overlies it, and at Sammis' yard the sand, 

 which is stained by limonite, shows a fine anticlinal fold. 



One of the most interesting clay banks is that on Fisher's 

 Island. The clay is of a reddish color similar to that on West 

 Neck and Center Island, and in its original condition was hori- 

 zontally stratified and overlain by 20 to 20 feet of laminated sand. 

 But the whole deposit has been disturbed by the ice sheet passing 

 over it, and the layers have been much crumpled to a depth of 

 about 30 feet, while below this they are undisturbed. The till 

 overlying it is in places 30 feet thick and contains large bowlders. 



Dr. Merrill mentions the presence on Gardiner's Island,f of 

 extensive beds of brick clay together with their associated sand 

 beds, (they are not being worked,) and notes the occurrence of a 

 fossiliferous stratum. 



Clay is also said to outcrop near Sag Harbor and around the 

 shore of Hog Neck in Peconic Bay. 



Between Southold and Greenpori are several deposits of a red 

 glacial day which is being used for brick. The clay contains 

 angular stone fragments and runs from 50 to 60 feet in thickness. 

 About one and a half miles east of Southold is a bed of mottled 

 blue pottery clay which has been used for a number of years in 

 making flower pots. The depth of this deposit is not known. 



At West Deer Park is a clay bank of unique appearance. In 

 July 1892 the section showed 



Yellow gravel 



6 feet 

 6 M 

 1 " 

 4 " 

 4 " 

 3 " 



Containing ) Flesh colored clay 

 concretions ) Red clay 



Black clay with pyrite 

 Black sandy clay. .... 

 Red sandy clay 



Total thickness, 



20 " 



t Previously cited. 



