166 ROCHESTER ACADEMY OF SCIENCE. 



Segmentation and intervals. Eskers tend to occur in segments, 

 separated by intervals of varying width. Discontinuity is the rule, 

 not the exception. No esker ridge may be traced for 100 miles, or 

 even 10 miles without interruption, the individual segments being 

 but a few miles long, rarely greater than 5 miles, and in many cases 

 only a fraction of a mile in length. In fact segments may be so 

 short as to be mistaken for elongated kames. Stone has stated that 

 in the long esker systems of ]\Iaine the eskers are seldom continuous 

 for more than 10 miles without a break (99). The segments may 

 or may not be in alignment. 



The intervals between segments are in many cases less than a 

 mile in length, but they may be 2 or 3 miles or even more in extent. 

 These intervals are apt to be occupied by scourways or drainage 

 creases (122). Again gravels more or less spread out and kames 

 are found in these stretches. 



Tributaries. Tributaries are an uncommon feature and. where 

 they occur, they are apt to enter the main course at a high angle. 

 They are in the vast majority of cases inferior in development to the 

 main ridge. 



Direction. In direction eskers trend with the general direction 

 of ice movement for the general locality in which they occur. Hence 

 their courses tend to parallel the striae, boulder trains and drumlins 

 of the surrounding region. There are however some notable depart- 

 ures from this direction, in fact some have been observed to extend 

 for miles in a direction transverse to the direction of ice flow. Some 

 have their entire course in a direction at nearly right angles to the 

 direction of local ice movement, again part of the course will be 

 transverse and a part conformable to the direction of the ice move- 

 ment. Some ridges have been observed that apparently extended 

 nearly to the edge of the ice, then turned abruptly through a large 

 angle and ran for miles parallel to the ice edge. 



Relations at point of origin. Esker ridges rise abrujitly from 

 the general surface. This is true not only at the point of origin of 

 the esker, but also at the beginning of each segment. As a rule the 

 ridges attain their full height within a few rods. They may arise la 

 a kame area, they may continue outward from a recessional moraine, 

 again they may originate in a bouldery field of irregularly heaped 



