450 GLACIAL GRAVELS OF MAINE. 



rather narrow at the north end of the plexus, and have rather steep lateral 

 slopes. Going southward we find the ridges on the average becoming 

 higher and correspondingly massive till we arrive within a few miles of the 

 contour of 230 feet. The ridges then grow broader as we still go south- 

 ward, the lateral slopes more gentle, and the hollows shallower. In the 

 more level country of eastern Maine there is an analogous but less-marked 

 change of form. 



5. Their relations to marine deltas of glacial origin. All the deltas 

 left by glacial streams in the sea, both the broad, fan-shaped deltas deposited 

 in the open sea and the narrower ones left in ba5^s or broad channels of tlie 

 ice, end at the north in reticulated ridges inclosing kettleholes and other 

 basins of various sizes and shapes. 



6. Their relations to lacustrine deltas of glacial origin. Numbers of 

 deltas were deposited by glacial streams in lakes inclosed wholly or in part 

 by ice. In the larger of these the deltas are more or less reticulated 

 toward their northern extremities. 



7. Their relations to overwash or frontal deltas of glacial origin. In 

 the interior of the State, as the ice retreated northward it often happened 

 that the glacial streams poured out from the ice front into valleys sloping 

 southward. Their sediments spread out and filled the valleys like the sedi- 

 ments of Alpine glaciers. Their stones have been worn and rounded by the 

 glacial streams more than they could have been worn by ordinary streams, 

 and often they were carried farther by the glacial streams than by the river 

 of the open valley be^^ond the ice front. Yet at the place of final deposition 

 the water was in no wa,j confined by ice and was practically an ordinary 

 river. These overwash or fluviatile deltas of glacial streams sometimes show 

 a rolling, uneven surface with shallow hollows, but no deep kettleholes or 

 conspicuous reticulations, except in the valley of the Androscoggin River 

 between Grorham, New Hampshire, and Gilead, Maine. The character of 

 the alluvium of this valley is elsewhere described. 



8. The material of the reticulated eskers. In general, the kame mate- 

 rial is coarser in the hilly regions and becomes finer southward. In the 

 western part of the State the reticulated ridges contain multitudes of bowl- 

 derets and bowlders, many of them much rounded, others with only a 

 little polish, as if carved by sand and gravel without having traveled far. 



