174 GLACIAL GEAVELS OF MAINE. 



If so, these local kames in Richmond date from about the same period and 

 were jDrobably deposited by short glacial streams in the sea at or near the 

 front of the retreating ice. Another short local kame is found near the line 

 of the Maine Central Eailroad about IJ miles south of East Bowdoinham. 



SEDIMENTARY DRIFT OF THE UPPER KENNEBEC VALLEY. 



The student of the drift of Maine who begins at the mouth of the 

 Kennebec River and travels northward will at once observe that the lower 

 portions of the valley are bordered by no siich system of terraces as those 

 of the classic upper Connecticut Valley. There is a low terrace of valley 

 drift near the present limit of high water. Above that the only terraces are 

 those eroded in the marine clay or till. The marine clay near the river 

 differs but little in composition from that found several miles away from it, 

 and is thus proved to be a rather deep-water deposit. The clays cover the 

 valley to a breadth of many miles. 



From Waterville northward there is a change in the character of the 

 sediments of the valley. Resting on the till or unmodified glacial drift is 

 a thick sheet of sedimentary clay, overlain by a stratum of coarser sedi- 

 ments. The latter composed the delta sands of the river when the sea stood 

 at 230 feet. Marine fossils have been found in the lower clays as far north 

 as Norridgewock. At North Anson fresh-water clam shells have been 

 found in brick clay several feet below the surface. This clay is apparently 

 of the same age as the rest of the underclay of the valley. But the unio 

 shells were found near the base of a terrace of erosion, so that it is not certain 

 whether they were deposited in the original underclay of the valley or in 

 a more recent erosion channel. From Norridgewock to the coast the low- 

 est layers of the clay are dark in color, often almost black, and often with 

 the odor characteristic of the clam flat. Farther up the valley the under- 

 clay becomes bluish gray in color and is slightly coarser, sometimes even 

 silty. The underclay extends continuously up the Kennebec Valley to a 

 point 2 miles north of Bingham; also up the larger tributaries for a consid- 

 erable distance above their junctions with the Kennebec. The underclay 

 partly covers the Anson-Madison glacial gravels, and near Solon overlies 

 local beds of well-rounded cobbles. It is thus evident that glacial gravels 

 were first deposited at various points in the valley, and that these were sub- 

 sequently covered by the clay. From being near three-fourths of a mile 



