158 J. L. Rich — Physiography and Glacial Geology 



produced the morainic loops behind which the present lakes 

 are impounded. Whether the ungraded valley heads above 

 the lakes are, as they appear, true cirques formed by local gla- 

 ciers, the writer is not prepared to venture an assertion. There 

 is, of course, the alternative hypothesis that all these features 

 were produced by ice tongues from the continental glacier 

 spilling over the lower parts of Mill Brook Ridge. With this 

 hypothesis conditions at Furlough Lake and the moraines 

 along Dry Brook do not seem to accord. The region certainly 

 promises to repay detailed investigation. 



A little less than two miles below Grant Mills at the junction 

 of the two valleys is a distinct morainic ridge convex down 

 valley (toward the west). Another occurs a. little over a mile 

 farther down. Both these morainic loops may possibly be the 

 products of local glaciers in the valley of Mill Brook. 



The Grand Gorge Lake. 



Since Schoharie Creek flows northward, the glaciers, when 

 they lay over the lower Schoharie, ponded its waters and com- 

 pelled them to find an outlet to the south. One of these out- 

 lets, first recognized by Darton,* was through the gap in the 

 Central Escarpment at Grand Gorge *at an elevation of 1561 

 feet. Grand Gorge Lake, as we may call the water body out- 

 letting here, lay within the narrow youthful valley of the 

 Schoharie, well below the level of the 2000 foot peneplain. 



In a number of the valleys tributary to the lake, prominent 

 deltas are found, while in others they seem to be lacking. In 

 the following paragraphs each of the deltas is briefly described 

 and its significance suggested. 



Grand Gorge Delta. — A finely developed delta of consider- 

 able size is found at an elevation of 1620 feet, 3/4 of a mile 

 north-northwest of Grand Gorge village. It is composed of 

 rather fine gravel almost exclusively local. A careful search 

 failed to reveal a single foreign fragment, though some large 

 igneous bowlders lie near the bottom of a cut made through 

 the delta by a post-glacial stream. 



The comparatively large size of this delta presents an inter- 

 esting problem. It is developed at the debouchment of a very 

 small stream only two miles in length and without tributaries, 

 while Bear Kill, a much larger stream, has no delta, or if one 

 is present it fails to show on the topographic map and has 

 escaped notice. If present it is, at best, inconspicuous as com- 

 pared with the one under consideration, though the latter lies 

 at the mouth of the much smaller stream. The only explan- 

 ation of this condition which comes to mind is that the delta 

 *Bull. Geol. Soc. Amer., vii, 1895, 505-7. 



