t'hey indicate not only the former elevation of the sea, but 

 give us some clue as to the depth and movement of water at 

 that place. 



All over the southern and eastern portions of the state 

 and well up the river valleys we have thick deposits of ma- 

 rine clays. In places these are rich in fossils. Many of the 

 forms are living today in northern waters. They point, to a 

 time when the water of the Maine coast was as cool as that 

 of Labrador today. A few fossil leaves have been found 

 which indicate a land temperature not far different from 

 that of today. At the time the clays were deposited the sea 

 stood at least 200 feet above its present level and received 

 torrents of ice-water from the glaciers still lingering in the 

 northern part of the state. Over the clays we have in some 

 places beds of marine sand. Often these show dune struc- 

 ture indicating old beaches where the wind blew the sand 

 into dunes like those on Cape Cod today. 



Where ever a stream enters quiet water its velocity is 

 checked and the sediment it carries is deposited. This ma- 

 terial collects until a delta is formed which may, as in the 

 case of the Nile or the Mississippi, reach great size. Each 

 stream flowing into the bays which indent our sea coast is 

 building its delta at the bay-head. At a time when the land 

 was lower and the sea extended far inland similar deltas were 

 formed and their eroded remnants indicate the former bay- 

 head. For example, there is a delta in the Saco Valley at 

 Bartlet, N. H., 705 feet above sea level and one on the An- 

 droscoggin at Bethel 720 feet in elevation. 



Not only did the present streams form deltas, but streams 

 long since gone have left their records in deltas and other 

 deposits. Toward the end of the glacial period a stream 

 flowed south from the vicinity of Hartland through Pitts- 

 field, Burnham and Unity, and finally formed a delta at its 

 mouth in Montville. Today the delta stands out on the hill- 

 side indicating an old shore line at about 700 feet. As the 

 sea receded new deltas were built by the main and tributary 

 streams along each valley. Each series of deltas marks a 

 halt in the retreat of the sea. Such low-level deposits are 

 found in the Androscoggin at Lewiston, in the Kennebec at 

 Skowhegan, in the Saco at Buxton at altitudes ranging from 

 525 to 575 feet showing a stand of the sea at about that level. 

 There are other deposits at higher or lower levels. 



Another line of evidence which has been developed lately 

 is found in the peat deposits of the coast. Peat is formed by 

 the decomposition of vegetable matter beneath a water cover. 

 As salt water and fresh water peat each has its character- 



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