34 W. UPHAM — giants' kettles eroded by MOULIN TORRENTS 



Within 5 to 10 rods west of Trap Rock street and at the height of 

 about 100 feet above the river several potholes from 1 foot to 3 or 4 feet 

 in diameter, originally filled with drift, have been recently excavated 

 under Mr Hazzard's direction. From these and from other potholes on 

 their chief area before described multitudes of ver}'- smoothly worn stones 

 have been taken, varying in size from small cobbles to nearly spherical 

 masses 2 feet or more in diameter, while others, waterworn on all sides, 

 but remaining oblong, measure 3 to 4 feet in length. 



On the higher rock outcrops west of the park limits no potholes have 

 been found. My search on the extensive tract of rock at and near the 

 school-house, 200 feet above the river, detected only one spot definitely 

 waterworn. This is about 30 feet west-northwest of the United States 

 Geological Survey bench-mark of leveling (890 feet above the sea). It 

 is a rounded hollow, about a foot in diameter, smoothly eroded by water 

 to a depth of 6 or 8 inches, where no stream can have flowed since the 

 departure of the ice-sheet. 



About a mile north of all these localities a hill of the same trap rock 

 rises between the railway freight-house of Taylors Falls and the river, 

 its top being about 50 feet above the end of the railwa\% or 110 feet, 

 approximately, above the river in the Dalles. Much of the rock surface 

 on this hill is waterworn, and it has numerous small potholes, scattered, 

 probably not less than 20 in all, mostly from 6 to 12 inches in diameter 

 and about one foot deep. Two others of similar size were also seen on 

 the northeastern slope of this hili, some 25 feet below its top and close 

 east of the Saint Croix valley road. 



In many other localities which have undergone glaciation })otholes are 

 found where they must be referred to moulin torrents and subglacial 

 streams. Short notes of these, so far as they have come to my knowledge 

 by observations, reading, and correspondence, are here added, that they 

 may be compared with the foregoing in the Interstate park, which seem 

 to me also referable to this i)hase of torrent work during the Ice age. 



MAINE 



Professor George H. Stone describes potholes on the island of George- 

 town, adjoining the east side of the mouth of the Kennebec river.* One 

 is near the level of high tide, and two others are about 60 feet above the 

 sea. These are 4 to 6 feet in diameter and 5 to 10 feet deep, and others 

 of smaller size occur in the same vicinity. The topographic relations 

 show that no stream can have existed there, excepting when confined in 



*" The glacial gravels of Maine and their associated deposits," U. S. Gaol. Survey, Monograph 

 34, 1899, pp. 324-330. 



