604 H. L. FAIRCHILD POST-GLACIAL UPLIFT OF NEW ENGLAND 



As all of eastern Massachusetts carries abundant evidence of standing- 

 water, ;the question of the genesis of the phenomena on the higher 

 ground lies between glacial lake waters and marine submergence. The 

 suggestion of an ice-dam lingering on the east and south while the larger 

 area was relieved of the glacier is at least unreasonable. The existence; 

 of partial or local ice-barriers on the seaward side for some low areas 

 does not meet the demands, because static water phenomena occur 

 abundantly over all the territory of New England that lies beneath the 

 imaginary surface joining the isobases of the maps (figures 1 and 2). 

 These phenomena are described in later chapters. 



If no measurable rise of land occurred previous to the removal of the 

 glacier from the coastal region, it follows that any glacial outwash plains 

 marking a water surface must record the highest water level. Kames 

 and moraine could be dropped in the deep water, but no plains could 

 be built in deep water in contact with the ice-front. Glacial outwas'i 

 plains were built only on higher ground or in shallow water and only 

 at the summit marine level. The earliest river deltas also mark the 

 early water level. Consequently, near the limit of glaciation any true 

 glacial plains and any heavy stream deltas of coarse materials are posi- 

 tive record of the deepest Post-Glacial submergence. 



If any rise of land did occur while the ice-sheet lay on the area or 

 before the plains were built, which is possible for the inland area, then 

 the submergence and subsequent uplift is greater than the present height 

 of the plains above the sea. 



Wherever the ocean lapped the land when the Labradorian ice-sheet 

 was melting, either outwash plains or stream deltas were built along the 

 sea margin. These bedded deposits are the inevitable and conspicuous 

 proof of standing water and of the highest stand of that water. Such 

 summit deltas are found on practically every stream course, and with 

 such accordant levels that prediction can confidently be made; and pre- 

 diction has been successfully made many times. The summit deltas 

 of Massachusetts and Ehode Island will be noted below. 



The hills of gravel (kames) built by concentrated glacial drainage in 

 submergence and then brought to the sea surface by the land uplift were 

 more or less worn down and leveled by wave and current work. The 

 great number of sandplains on low ground are of this nature. The 

 iS^ewtonville plain (53) is a good example of leveled and truncated 

 kames. The knolls were built in deep water and the leveling took place 

 subsequently in very shallow water. The plain is not a constructional 

 glacial plain, but an erosional marine plain. One or more points '*(-' 



