130 G. H. Stone — Glacial Sediments of Maine. 



in the midst of the series, and most of the systems contain in 

 their courses one or more marine deltas. When there are 

 more than one delta they are separated by intervals of several 

 miles. 



It should be carefully noted that these gravel deposits are 

 separated by reaches of undisturbed till and marine clay. 

 This proves that these deposits were not once continuous and 

 they have not become discontinuous by recent erosion of the 

 intervening parts. In short, for some reason a glacial stream 

 here deposited its sediments at intervals, not continuously. 



Systematic non-continuity is a feature of the glacial gravels 

 of the coast region of Maine, and is found in only three cases 

 above 230 feet. 



All of the longer gravel systems, including the great osars 

 and osar-plains, become discontinuous as we approach the ocean. 



The general law is that as we go south from the contour of 

 230 feet the glacial gravels become more and more discontinu- 

 ous, i. e., the intervals become longer, the gravel deposits 

 become shorter and smaller. Almost all the systems end north 

 of the present shore, and but a few feet above sea-level. In 

 Belfast and Penobscot bays several gravel systems enter the 

 sea, but these bays extend considerably north of the general 

 line of the coast. The above remarks apply only to the coun- 

 try east of Portland. I have only partially explored the coast 

 south of Cape Elizabeth. 



The elongated cone and the dome are the prevailing shapes 

 of the smaller masses of glacial gravel in the coast region. So 

 characteristic is the shape that they may well be termed lentic- 

 ular kames. Their stratification is often somewhat quaquaversal. 



Since for many reasons (more fully set forth in my report), 

 a line of these separated kames is considered as having been 

 formed by a single glacial river, they are classified as a single 

 system, hence a discontinuous system. 



The cause of systematic non-continuous sedimentation furn- 

 ishes one of the most obscure problems connected with the 

 glacial sediments. The subject is discussed at length in my 

 report. 



The maximum development of glacial sediments is found 

 near the contour of 230 feet, and the amount diminishes in 

 opposite directions from this line. This fact leads to several 

 interesting inferences, but lack of space prevents further dis- 

 cussion of the subject at present. I will close by remarking 

 that it will yet be possible by a study of the terminal moraines, 

 the glacial marine deltas, etc., to map pretty accurately the 

 general outline of the ice-front as the ice retreated northward 

 before the sea. 



Y. The Osars. — These are the longer two-sided ridges. Several 

 of them are. more than 100 miles in length. Near the north 



