•76 MAN AND THE GLACIAL PERIOD. 



have been concentrated in pretty definite lines, often de- 

 termined by the contour of the bottom, leaving a slacker 

 movement in intervening areas, which were evidently pro- 

 tected in some cases by projecting masses of rock. In 

 these areas of slower movement there was naturally an 

 accumulation at the same time that there was vigorous 

 erosion in the lines of more rapid movement. 



There was doubtless a continual transfer of material 

 from the end of the drumlin which abutted against the 

 moving mass of ice to the lower end, as there is in the 

 formation of an island in a river. If time enough had 

 elapsed, the whole accumulation would have been levelled 

 by the glacier and spread over the broader area where the 

 more rapid lines of movement became confluent, and 

 where the differential motion was less marked. Drumlins 

 are thus characteristic of areas in the glaciated region 

 whose floor was originally only moderately irregular, and 

 where there was an excessive amount of ground moraine 

 to be transported, and where the movement did not con- 

 tinue indefinitely. It has been suggested, also, that some 

 of the long belts of territory in New England and central 

 New York covered by drumlins may represent old terminal 

 moraines which were subsequently surmounted by a re- 

 advance of the ice, and partially wrought over into their 

 present shape. 



It is in New England, also, that kames are to be found 

 in better development than anywhere else in America. 

 These interesting remnants of the Glacial age are clearly 

 described by Mr. James Geikie. His account will serve 

 as well for New England as for Scotland. 



The sands and gravels have a tendency to shape them- 

 selves into mounds and winding ridges, which give a 

 hummocky and rapidly undulating outline to the ground. 

 Indeed, so characteristic is this appearance, that by it 

 alone we are often able to mark out the boundaries of the 

 deposits with as much precision as we could were all the 



