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



dric, vertical, or in part slightly overhanging surfaces, as if halves of 

 two very large potholes, each open toward the south, were joined, giving 

 a combined diameter of 30 feet from west to east. The curved and 

 cuspate rock face, rising 15 to 20 feet, from about 30 to 45 or 50 feet 

 above the river, has variegated colors in different parts — reddish and 

 black (by iron and manganese stains), a dark dull green (the natural 

 color of the rock), bright yellow (patches of lichens), and, in some 

 spots and streaks, light gra}'' or even wliite (lichens, and efflorescence of 

 carbonate of lime from water leaching through thin drift and the rock 

 crevices). On account of their smokelike and fiery coloring, these halves 

 of giants' kettles are called ''the Saint Croix Fireplace." For the ex- 

 planation of their erosion I can only suggest that here, as in places of 

 moulin torrent action in Massachusetts and New York, effective erosion 

 nearly as in a i)othole of the largest size took place on a mural surface, 

 with only ice, as we must suppose, to form the other side of the moulin. 

 It is quite sure that they were worn as half-potholes instead of having 

 undergone demolition and removal of the wanting part. On a smaller 

 scale such mural segments of cylindric water-wearing are seen in several 

 other places within this little area. 



Close south of one of the foot-bridges leading to Angle Rock the narrow 

 gorge, 15 to 20 feet deep, which the bridge spans, is enlarged, nearly like 

 a great pothole about 15 feet in diameter, by the same cylindric water- 

 wearing. The open passage of the gorge leading to the north is only half 

 as wide, with roughly fractured walls due to nearly vertical joint planes. 

 This place has been named by visitors the '' Devil's Kitchen." 



Again, a curious freak of the water-wearing is displayed by the " Bake 

 Oven," a pothole 6 by 7 feet in diameter and 10 to 15 feet deep from its 

 unequal rim. It is filled lower by soil and earth, forming a floor, on the 

 continuation of which, by crouching, one may pass out eastward through 

 an opening, waterworn under a thick roof of rock, to a lower space ten 

 or 15 feet away. Only six feet of rock on the north side of the " Bake 

 Oven " separates it from the hole that was excavated and probed to a 

 depth of 65 feet, as before described. 



Among the smaller potholes of this most interesting area, near the 

 wharf, is one which is named the " Hourglass Well," situated about 10 

 feet northwest of " the caldron." Its diameter is about three feet at the 

 mouth, and somewhat increases to the de})th of 3 or 4 feet ; it is then 

 constricted, within two feet lower, to a diameter of only 18 inches, but 

 widens again below to nearly three feet, the bottom being about eight 

 feet below the highest part of the mouth. The constriction may have 

 been due to a harder band of the rock which comprises successive lava 

 flows. It should be noted, however, that a similar form of a pothole at 



