PREGLACIAL LAND SUEFACE AND SOILS. 265 



of the geological work of the ice on the land of that period and also the 

 offshore drift then thrown into the ocean by the ice-sheet itself, by ice floes 

 and icebergs, and by glacial rivers, the whole having since been more or 

 less modified by the waves and currents of the sea. The subsequent 

 retreat of the sea to its present position has exposed these deposits for 

 convenient study, and thus has furnished a good example of the multi- 

 form work going on off an ice-bound coast. Our geological conceptions 

 are thus enlarged hj the same process that added the clay loams to the list 

 of the soils of Maine. But the problem before us involves more. The 

 final melting of the ice over the land left the waters free to follow the val- 

 leys of natural drainage. Rivers much larger than the present rivers then 

 flowed into the sea from 30 to 100 miles above their present mouths and 

 were depositing deltas in the sea not far from the coast line as it at that 

 time existed. These deltas are now exposed for our study, and are to be 

 distinguished from marine and glacial sediments. Moreover, before the ice 

 had all melted, lakes gathered on the land, confined wholly or in part by 

 ice. Thus the various kinds of drift of the glacier are to be distinguished 

 in the midst of preglacial soils and lacustrine, fluviatile, and marine sedi- 

 ments, often since modified by the action of the wind and streams, or 

 strewn by drift from floating ice, or eroded in part and carried away beyond 

 our sight, or bodily misplaced by landslips. Everything which directly or 

 indirectly produced a single one of the field phenomena must be of 

 interest to us. 



PEEGLACIAIj LAISTD STJRFACE AND SOILS. 



The longer a region has been above the sea the more nearlj^ are the 

 surface features due to upheaval and unequal elevation replaced b}^ those 

 due to subaerial erosion. The coming of the ice-sheet found Maine in that 

 stage of development called geological "old age." The land had been 

 deeply sculptured, here with a heavy stroke, there with a lighter touch, and 

 the rock yielded in different degrees to the attack of the chisel. Only the 

 ruins of the folds and cones produced by mountain-making forces remained. 

 The outlines of these remnants of a prime-s-al land were about like the 

 present surface forms of the State, save that the hills were more rougli and 

 angular in outline. Steep cliffs of erosion abounded which were ragged 

 with weather-rounded bowlders. The long conflict which for p'eoloffical 



