7() NEW YORK STATE MUSEUM 



of Ballston a si ream c'scajHis from this gorge by a narrow detile 

 into the circular deja-ession in the bottom of which lies Round 

 lake, a body of watei* whiiii in luru is drained by a narrow 

 valley into the Hudson at Mechanicville. This system of channels 

 antedates the last ice covering of the district, for portions of the 

 region including the flats bordering Round lake are covered with 

 glacial boulders. Singularly enough these depressions were not 

 tilled with the elays of the Mohawk delta stage probably because 

 as will be shown later the ice sheet lay over the region while 

 these clan's were deposited on the east and south. 



The Ballston rock cliannel is dependent, iu part, on structure. 

 The Hudson river slates, essentially flat on the east of this trough 

 except for small overthrusts, are seen standing vertical within it 

 north of Ballston lake. Erosion iu Pleistocene time has exca- 

 vated the channel along the vertical beds, which are evidently sep- 

 arated from the horizontal strata on the east wall of the valley 

 by a fault. Ebenezer Emmons^ recognized the existence of a fault 

 extending southwestward from Saratoga towards Schenectady but 

 he makes no mention of the Ballston rock channel. 



lifuind lake channel. The large circular depression in the bot- 

 tom of which lies Round lake [see pl-l] opens eastward through 

 a narrow valley into the Hudson gorge at Mechanicville. Little 

 or nothing is known concerning the real extent of the depi*ession 

 ill I lie bed rocks of which this largely drift-masked cavity is a 

 pari. The Hudson river rocks rise on the west between Round 

 lake and the Ballston channel and may be seen in the narix^w de- 

 file cut by Anthony kill, a stream Avhich now drains the Ballston 

 channel from East Line to the divide south of Ballston lake. The 

 I)lain between Round lake and Saratoga lake is at least in part a 

 till-covered surface as about Malta. It seems probable that Round 

 and Saratoga lakes are unfilled deiu-essions nmrking the site of an 

 old valley west of the jiresent Hudson gorge. In the later develop- 

 ment of ihe glacial lakes in the upper Hudson and Chanii)lain 

 valleys (he various eliaiinels from Fish creek southward through 

 the liallstoii and {{ouud lake channels probably will be found on 

 further study to have served as iemporary waterways at a time 



'Ajfric. N. V. 18-1(5. ] :i;i5. 



