690 GEOLOGY OF OLD HAMPSHIRE COrXTY, MASS. 



erosion. In this lower horizontal bed the alternation of coarser and tiuer 

 layers is very marked, and southward the finer layers gradually change to 

 clay, while the coarser grow thinner and finer and at last run out or blend 

 with the clay layer forming its lower and sandier third. At the same time 

 the lioundary between tlie horizontal and cross-bedded portions of the bed 

 rises slowly southward, since each layer of the latter coming to the bottom 

 of its slope bends sharply to a horizontal position, and, gradually dwindling 

 to become the sandy portion of a clay layer, runs on between laj-ers of the 

 clay, which, coming from the south, bend at the foot of the slope, rise up 

 for a distance upon it, and grade into a layer of finer sand which forms the 

 upper part of the sloping sand layer. Thus, going- south, the horizontal 

 layers gain at the expense of the cross-bedded layers above, and the clays 

 gain at the expense of the coarse delta sands, and one has the clearest 

 illustration of the blending of the shore sands and the deep-water clays of 

 the Champlain epoch, and evidence of their synchronism with the later 

 events of the Glacial epoch. 



The facts detailed in the above section enable us to construct the 

 following pictures of the succession of events over this area: 



1. The formation of a drumlin as a part of the ground moraine of the 

 first or great glacier. 



2. The recession of the ice to allow of the formation of the bowlder 

 bed which lies at the foot of the drumlin and may be a terminal moraine, 

 or may be due to water action concenti'ating it from the drumlin itself 



3. The formation of a true sea beacli of great extent — the pink sands. 



4. A second advance of the ice, rising over the drumlin and eroding 

 the frozen beach sands. 



5. The second recession of the ice, and the deposition by the flood 

 waters, from its melting, of a great body of sands. 



6. The rise of these waters so tliat an equally great body of clays 

 was deposited upon the sands. 



7. A third minor advance of the ice over these clays, molding them 

 into the sands below, removing them entirely over the drumlin, and south 

 of it for a long distance gouging deeply into the sands and covering them 

 with a laver of till derived largely from the dramlin, finally riding up onto 



