THE CAMP-MEETING (JUTTING. 685 



same at tlie smith end of the druinhn or southwunl. Tliis tuiirth till is made 

 up of material derived from the drumlin and mohled with the clay and sand 

 below, and so grades southwardly into the contorted (days uncontaminated 

 with glacial debris, whose planed-off upper surface is the continuation of 

 the fourth surface occupied by the ice in the whole distance south of the 

 cexitral gorge to the place where this ice- worn surface sinks below the level 

 of the section. 



Because of this blending of the clays with the second sands beneath 

 them by the fourth ice, the relative importance of the third surface occupied 

 by the ice in the midst of the second sands can not be clearly made out. 

 It is seen in the sloping layer of till that extends down through the second 

 sands, ending at the north edge of the brook gorge, and is marked "third 

 ice-worn surface" on the/ main section. Some pai't of the deep erosion of 

 the second sands between this point and the south end of the di-umlin seems 

 due to this third ice advance. 



In the opposite side of the cutting, 50 feet west of and parallel with the 

 above, the third layer of till ends abruptly in the sands, soon after thicken- 

 ing to 7 feet and rising nearly to the surface in a way peculiar and difficult 

 to explain. It is here a compact, stony clay, in which, near the end, I 

 counted twenty bowlders 12 to IG inches long, all of glacial shapes and 

 many striated. As seen in the wall of the cutting, it ends in three long, 

 sharp teeth projected southward, receiving between themselves correspond- 

 ing projections of the sands; and these projections are made up of lamiuse, 

 which begin agamst the till and extend from it with j^erfect regularity, 

 exactly as if it were the fluted face of a sea cliff and the sands had been 

 laid down against it. There seems to be no cpiestion here of a thrusting of 

 the ice into the sands after their accunuilation, but it would seem that the 

 third till represents a second advance of the ice after a slight retrog-ression, 

 and that here it pushed itself over the sands of the lake or estuary as before, 

 with the difference that now the water stand was higher and the snout of 

 the glacier was thrust out into the lake, gouging and crumpling the beds at 

 its bottom. It ended here for a time and then retreated, leaving the till, 

 which it had gathered mainly from the di-umlin, covering the sands to this 

 point. The deposition of the sand continued uninterruptedly except so far 

 as the space was occupied by the ice, and the sand increased around and 

 over the till as soon as the ice disappeared. 



