Editorial. 



In a personal letter from Bernard B. Smyth, of the Kansas 

 Academy of Science, certain phenomena of the margin of the 

 drift are described, which afford a criterion of age that is new, so 

 far as we know. Mr. Smyth has recently been engaged in trac- 

 ing the border belt of the drift in the vicinity of Topeka. This 

 consists of a distinct well-defined train of bowlders with very 

 little other drift. This had been traced to a point southwest of 

 Topeka, where it disappeared. On making another attempt to 

 recover the lost train, Mr. Smyth was surprised to find it in an 

 unexpected place, resting on the bed-rock of the bottom of the 

 valley of Shunganunga creek, covered up "with about twenty feet 

 of native prairie earth washed front surrounding hills." Further 

 tracing showed that the train makes a sinus two miles deep and 

 a mile and a half wide, beyond which it resumes its general 

 course. This embayment Mr. Smyth attributes to the influence 

 of a high point of land, which affected the ice rather by the 

 reflection of the sun's rays than by physical opposition, since the 

 line of bowlders does not approach the hill closer than one- 

 third of a mile, generally not nearer than one-half of a mile. 

 Analogous behavior of the ice in the vicinity of prominences 

 was observed by the writer in Greenland. The point of most 

 especial interest, however, is the burial of the border train of 

 bowlders under so great a depth of native prairie earth from the 

 surrounding hills. This indicates either that very favorable con- 

 ditions are offered by this valley for the derivation and deposi- 

 tion of prairie earth, or that, the bowlder belt has a very con- 

 siderable age. At any rate, here is a basis of estimating both 

 the actual and the relative ages of glacial deposits when so situ- 

 ated that the burying material may be discriminated as ordinary 

 surface wash. From this region to Montana, the surface outside 

 the drift border slopes toward it, and affords a wide field for the 

 application of the method. T. C. C. 



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