170 . GLACIAL GEAVELS OF MAINE. 



This series penetrates a rather level region and does not cross hills 

 more than about 100 feet high. For its whole course it has been under the 

 sea, and its bases are flanked and more or less covered by clay, often con- 

 taining great numbers of marine fossils. The clay is more abundant along 

 the line of the gravels than away from it on ground as favorably situated 

 for the deposition of sediment by the sea. At the south end of Three- 

 mile Pond, in Windsor, I had some difficulty in tracing the course of the 

 osar river, as no gravel appeared on the surface. But passing obliquely 

 up the hill at the south end of the pond was a belt about one-eighth of a 

 mile wide which was free from bowlders, whereas there was a considerable 

 number of bowlders on each side. Examination of the ravines of erosion 

 on the hillside showed that here was a strip of clay much deeper than the 

 marine clay on each side, which was not thick enough to conceal the 

 larger bowlders of the till. Groing southward along the line of thick clays, 

 the glacial gravels soon reappear, and plainly underlie the clay. I infer 

 that the gravels were first deposited in a rather narrow channel in the ice. 

 This channel was subsequentlj^ greatly enlarged, although still bordered 

 by ice walls. In this broad channel kame border clay was deposited. In 

 the southern part of Vassalboro, not far from Webber Pond, a fine blue 

 clay, apparently the kame border clay, is highly fossiliferous. Finally the 

 ice all melted and the whole region lay beneath the sea. A thin sheet of 

 purely marine clay was now spread over the kame border clay and all the 

 previously deposited drift. 



At several points along the line of this series short ridges are found 

 at right angles to the main ridge. These were probably deposited by 

 small tributary streams, yet in some cases they may be due simply to 

 an abrupt enlargement of the main channel. Near tlie line of this series 

 are a number of pinnacles and cones of till of quite irregulai' shape, which 

 are more fully described elsewhere. Wells dug along the line of this 

 series show that in general the sedimentary clay overlies the gravel. One 

 well in Windsor, near the junction of this glacial stream with the main 

 river, is dug through gravel into fine blue clay. Whether the gravel was 

 deposited in this position by the glacial stream, or was washed down upon 

 the clay by the waves of the sea, is uncertain. 



The leng-th of the branch is 14 miles. 



