GLACIAL GEOLOGY OF THE SCHENECTADY QUADRANGLE 15 



plain which lies at the foot of the Glenville hills to the Mohawk 

 channel. The materials of the till of this area are chiefly clay and 

 fragments of shale and shaly sandstone, evidently derived from the 

 local rocks. Cobbles and boulders of gneissic and quartz rock occur. 



Drumlins. There are a number of hills of a well-defined drumlin 

 type. The most conspicuous of these *fs that in the town of Glen- 

 ville crossed by the east-west road north of Alplaus. The hill is of 

 an elongated elliptical shape, about one mile in length and one-quar- 

 ter of a mile in diameter. There is an exposure of bedrock in the 

 road west of the hill ; taking this as the level of the base of the hill 

 its thickness at the summit is about 40 feet. The direction of the 

 long axis corresponds closely with that of the glacial striae observed 

 elsewhere. A partial section of the hill is afforded by the cut made 

 in grading the road and reveals the till nature of the material. 



Another drumlin of smaller dimensions but similar features occurs 

 one and a quarter miles to the west. 



The hilly region in the town of Niskayuna crossed by the road 

 that runs south from Aqueduct presents hills of till of drumlinlike 

 outlines. The group of hills south of the village of Niskayuna, the 

 highest of which has an elevation of 500 feet, is probably of this 

 type. 



Morainic hills. In the vicinity of the village of Burnt Hills the 

 topography is marked by hills of irregularly rounded or moundlike 

 forms separated by basin-shaped depressions or wide intervening 

 hollows. They are most typically developed in the area south- 

 east of the village toward the Ballston channel. Owing to 

 their moderate size they are not indicated by the contour lines 

 of the sheet. Of the materials that enter into the composition 

 of these hills the amount of gravel and sand is conspicuously large. 

 In places, as observed at the surface, little else is visible. The gravel 

 consists of coarse sand, hard, worn pebbles and small cobbles and 

 worn fragments of shaly rock. In the locality here referred to no 

 exposure sufficient to determine whether the materials are stratified 

 in arrangement was found ; but farther to the west beyond the road 

 that runs south from Burnt Hills a cutting was found in which the 

 materials showed definite stratification. Also at the side of the road 

 that runs eastward from Burnt Hills there is a sand and gravel pit 

 that shows a layered arrangement. The area in which gravel 

 abounds extends to the west and southwest and is cut by the Alplaus 

 gorge. South of the gorge the fields are strewn with coarse gravel 

 and cobblestones. 



