GLACIAL GEOLOGY OF THE SARATOGA QUADRANGLE 



21 



the area crossed by the railway three lakelets without outlets oc- 

 cur. Other depressions are in the form of conspicuous broad chan- 

 nels, on the valleyward slope of the formation, with dry bottoms 

 thickly strewn with cobbles and boulders. They are evidently the 

 results of erosion by flooded waters of late glacial times. An ex- 

 ample occurs about one-half of a mile north of South Corinth, the 

 lower end of the channel being crossed by the highway. About 2 

 miles south of Porter Corners two parallel dry erosion channels 

 occur, separated by an intervening ridge. They are indicated by 

 che contour lines of the sheet. 



Fig. 2 Diagram illustrating mode O'f origin of kame terraces, as described 

 in the text. (Adapted from Salisbury) 



A kame terrace has been defined as "a terrace of sand and 

 gravel, deposited by a glacial stream between valley ice (generally 

 stagnant) and the rock slope of the valley." 1 The kame terraces 

 here considered are in accord with this definition. While a thick 

 mass of ice still lingered in the central basin, the mountain to the 

 west became freed of ice. Between the base of the bared rocky 

 slope and the lateral margin of the ice lobe a valley formed, due to 

 the more rapid melting of the ice where exposed to the higher tem- 

 perature of the bared slope. Waters derived from the melting ice to 

 the north, following the lowest line of drainage, occupied this val- 

 ley. The stream thus formed deposited along its course more or 

 less of the sand and gravel transported by it. As the ice continued 

 to melt, t)he stream shifted more and more valleyward, thus build- 

 ing a broad mass of deposits, somewhat of the form of a terrace. 

 The varied factors involved in the construction of the mass, as 

 changing currents, irregularities of ice margin, detachment and 

 subsequent melting of ice blocks, washing out and slumping of the 

 deposits, account for the present structural and topographic feat- 

 ures of the formations. 



It is interesting to note that a miniature kame terrace was devel- 

 oped on the eastern slope of the eastern Adirondack highlands, 



1 Salisbury: Geol. Sur. of New Jersey, 5:123. 1902. 



