GLACIAL GEOLOGY OF THE SCHENECTADY QUADRANGLE 21 



came the surface materials of the sand plain. At the same time the 

 currents of the Mohawk, now confined to their channel, cut power- 

 fully into the western edge of the mass of deposits. Gradually the 

 basin at Schenectady, bounded by the bluff which still parallels the 

 course of the river, was eroded out. 



To what depth below the level of the present surface of the basin 

 the mass of deposits extends is not known. I am informed by Mr 

 J. L. Fitzgerald, City Engineer of Schenectady, that a boring was 

 made under his direction, in connection with locating a site for a 

 gas tank, at a point near Villa road, some 400 feet from the foot of 

 the bluff, and that a depth of 50 or 60 feet of sands and clays was 

 penetrated. The sands are described by him as '^ quicksands," con- 

 sisting of rounded grains. He states that the sands occurred in lay- 

 ers, with thin partings of clay. I am also informed by Mr B. B. 

 Steers, manager of the Schenectady Gas Company, that a boring 

 was made near the site of the present gas works on South Center 

 street and 150 feet of sand was penetrated and no rock was struck. 

 The boring was tubed for the purpose of obtaining water but the 

 supply was meager and the well was abandoned. 



It would appear from these data that the rock basin near Schenec- 

 tady is of considerable depth. It seems probable that this depression 

 was already partly filled with deposits when the epoch of delta- 

 building in Lake Albany began. 



2 The Round lake region. In the Round lake region clays are 

 exposed on the floor of the depression and in places on its slopes. 

 The level to which the clays rise is about the same as in the deposits 

 near Schenectady. In a cutting where the road entering Round 

 Lake village from the west descends the hill, horizontally stratified 

 dark clays are seen at approximately the 300 foot level. They are 

 overlaid by sandy clays grading into sands. The clays appear in 

 several places, on the opposite side of the depression, in cuttings 

 made in grading the macadamized road. West of Maltaville, be- 

 yond the creek, where the road ascends the hill, a very interesting 

 section is presented. At the base (at about the 220 foot level) a 

 thickness of about 12 feet of dark evenly stratified clays are shown. 

 Above this are 3 feet of fine-grained, yellowish clayey material, not 

 exhibiting stratification. Overlying this and unconformably with it 

 is a layer about 4 feet thick composed of sand, gravel and small 

 cobbles. 



There is another section similar to this on the same road half a 

 mile to the south. 



It is evident that in this locality the clays have been subjected to 



