14 NEW YORK STATE MUSEUM 



- Hills of Sand and Gravel. Karnes. In the uplands region there 

 are a number of isolated groups of hills, composed mainly of sands 

 and gravel and presenting the characteristic features of kame topo- 

 graphy. Their locations are shown on the accompanying map. The 

 largest of these kame areas lies northward from the valley of the 

 eastern branch of Tomhannock creek and near the village of that 

 name. The surface of this area, made up of hills and hollows of 

 irregular shapes and without order of arrangement, is conspicuously 

 different from that of the surrounding country, the features of 

 which are largely controlled by the underlying rock surfaces. Many 

 of the hills have steep slopes and a degree of evenness of front that 

 indicates deposition of the sand and gravel materials against a 

 stationary mass of ice. 



These groups of hills are interpreted as recessional moraines, 

 marking a temporary cessation of retreat of the general ice sheet at 

 the time of melting in the localities where the heaps of debris occur. 

 In the case of the moraine just described it seems probable that its 

 development was incident to the slower melting O'f the thick ice 

 that filled the preglacial valley now followed by the creek. There 

 is evidence that the moraine originally extended farther south 

 across the valley and that it has been reduced at its southern edge 

 by stream erosion, the finer materials having been carried by the 

 stream to glacial Lake Tomhannock, there building a delta, as 

 described below. 



Ridges. In- a number of localities there were observed accumu- 

 lations of sand and gravel with admixture of clay and fragments 

 of slate rock having the general topographic form of ridges. In 

 some of them, as the one near Melrose and that north of Speigle- 

 town, the materials, as exposed in gravel pits, show a stratified 

 arrangement. The location of these ridges (see map) presents a 

 certain uniformity; that is, they are all located on the uplands but 

 within a short distance from the clay and sand deposits of the 

 Hudson valley. Their elevation above the latter varies from 20 to 

 60 feet. The direction of the ridges is in general parallel with that 

 of the edge of the valley deposits. 



The inference drawn from these data is that these ridges repre- 

 sent deposits made marginal to the lobe of ice that occupied the 

 Hudson valley after the disappearance of the general ice sheet from 

 the uplands. A fuller statement of the evidence of the persistence 

 of an ice lobe in the Hudson valley long after the melting of the 

 ice from the uplands will be given later in this report. It is believed 



