SHORT ISOLATED OSARS OR ESKERS. 361 



sea level. The lenticular and broadly arched types prevail. The lateral 

 slopes are usually quite gentle. In many cases the waves washed over the 

 tops of the kames and osars, eroding a portion of the upper parts of the 

 ridges and molding their external foi'ms near to that of the sand bar of the 

 coast. For some time I supposed that all the gravels that had been beneath 

 the ocean had been thus acted upon. Later I have discovered mounds 

 showing the same features in valleys that were occupied by long narrow 

 straits and inlets, yet so protected from marine erosion that their change 

 in form from this cause must have been small. Thus the north-and-south 

 valley of Georges River was at one time a strait extending from the Bel- 

 fast Bay of that period. For 10 or more miles it was only from one-fourth 

 mile to near a mile wide. On the east were the high hills of Hope, Cam- 

 den, and Lincolnville, and a high ridge lay on the west. The strait was 

 well landlocked and protected from the outside waves. The gravel cones, 

 domes, and short ridges of this valley are more or less covered by marine 

 clay and have the same outline that is common elsewhere in the region that 

 was under the sea, and there are no gravels washed down upon the adjacent 

 clays. The same is true of the discontinuous system in the Medomac Val- 

 ley above Waldoboro. While, then, it is certain that in exposed situations, 

 as on the tops of the hills at Portland, the tops of the gravels were more or 

 less eroded and molded by the sea, yet we must conclude that in addition 

 to this effect there was a difference in the average forms of deposition ot 

 the gravels of the coast and those of the interior. The former are less 

 steep and approach the flowing outlines of the drumlins. 



Divided into classes according to their external features, the glacial 

 sediments ai'e as follows: 



SHORT ISOLATED OSARS OR ESKERS. 



These are perhaps the simplest form of the glacial gravels. The term 

 "isolated" is applied to them because no other gravels are known to be near 

 them in such relations that their formation can be attributed to the same 

 glacial stream. They have the form of a cone, a dome, or often a short 

 ridge, or sometimes several short ridges having a linear arrangement (length- 

 wise of the ridges), or occasionally a few somewhat parallel ridges inclosing 

 basins. They vary in length from a few feet up to a mile or two. A dis- 

 tinguishing feature of the class is that they have no fan-shaped or enlarged 



