248 THE JOURNAL OF GEOLOGY. 



within the last few miles of their traceable courses, they certainly- 

 must entirely disappear within three to five miles of their appar- 

 ent endings. We omit here the overwash gravels that were de- 

 posited in front of the ice beneath the present ocean. 



It is to be noted that these gravels are in lines or systems, 

 and often toward the north pass into continuous osars. They 

 are regarded as having been deposited by a single glacial river, 

 that is, all that are classed as a single system. The intervals 

 between the separated gravel masses are not due to erosion of 

 a once continuous body. But the problem relates to the reasons 

 why a single glacial river deposited sediments at intervals here 

 and there within its channel. 



In placing the problem before us, we have to consider the 

 extent of the region in question. The above-named character- 

 istics are associated with each other along two hundred miles of 

 coast. Every few miles throughout this district we come to 

 places where a glacial river has left its sediments. All these 

 gravel systems exhibit the first two of the above named charac- 

 teristics, and all but four or five, the last. Three osars end at the 

 shore but near the north end of Penobscot bay several miles 

 north of the general fjord line. Two others, perhaps the largest 

 systems in the state, come down to the shore and the soundings 

 seem to support the conclusion that they extend for a short dis- 

 tance under the sea. Horizontally, these changes mostly take 

 place within a belt not far from thirty miles in breadth; vertically in 

 most cases between sea level and the two hundred feet contour. 

 The last named, the ending of the gravels, occurs between con- 

 tours hardly fifty feet apart. 



It is granted that the sea in late glacial time stood along the 

 outer coast line, a little more than two hundred feet above its 

 present level. In the interior its elevation was more than twice 

 this height. All the beaches along the outer coast, whose height 

 I have measured, have nearly the same elevation. In other words, 

 the surface of the sea in late glacial time was substantially par- 

 allel to its present surface in the direction of the coast, though 

 at a higher level. 



