GLx\CIAL WATERS IN BLACK AND MOHAWK VALLEYS" 1 5 



The deltas built by the Boonville river in the falling Mohawk lakes 

 will be discussed later (see pages 35). 



The sharp hills about Boonville are kanie-moraine and similar to 

 those previously noted in the Forestport district. Sperry hill north- 

 east of the village rises 280 feet over the village, or to 1400 feet. 

 At present the canal is chiefly used for carrying sand from these 

 hills to Utica and eastward cities. 



Sand plains in Port Leyden lake. The east shore of this lake 

 received an enormous supply of detritus. The deltas are developed 

 on a magnificent scale and form a practically continuous sand plain 

 along the east side of the valley, as shown in plates 3, 20 and 21. The 

 plain is trenched by the Black river tributaries and broken by numer- 

 ous deep, irregular basins or kettles produced by the melting of 

 blocks of ice which had become detached from the waning glacier 

 and surrounded, or sometimes wholly buried, by the delta sands. 

 These ice block kettles probably surpass in size, number and excellent 

 character any other district in the State. ^ (See plate 21.) 



Some of the higher sand areas along the east edge of the Port 

 Leyden quadrangle and eastward may perhaps have genetic rela- 

 tionship to local waters held along the ice margin, or possibly even 

 held between the Black valley ice lobe and alpine glaciers from the 

 Adirondacks, but the broad, smooth plains indicated on the map 

 must certainly correlate with the Boonville outlet. About Bucks 

 Corners the sand plain abuts .against moraine at 1220 feet. North- 

 east of Port Leyden the good delta plain is 1215 to 1220; south of 

 Brantingham it is up to 1225 to 1230 feet. Above these levels the 

 plain becomes duny, rolling and irregular. Beyond the upper limits 

 of the plains dune knolls are common. The northward rise of the 

 sand plains on the Port Leyden sheet averages about five feet per 

 mile, and as they are thought to have been deposited at about the 

 same time this slope may be taken as the amount of the deformation. 



The depth of the lake deposits must be great, as the kettles, except 

 a few at the north edge of the map, do not hold water, though some 

 of them are over 60 feet deep ; and rock or till rarely appear except 

 in the deeper stream cuttings. Some of the kettles show cobbly 

 kame gravels and boulders on their walls. 



The sand plains are now destitute of forest and occupied by grass 

 and scrubby growth of scattering trees. 



^A good example of a large kettle in a small delta in central New 

 York is described in Jour. Geol. 6 -sBg. 



