510 J. Q. Goodchild—On Drift. 



to the drumlins in everything but in the proportion of water-sorted 

 material, and in their more irregular and steeper sided form — all in- 

 cline one to the belief that these sand and gravel mounds have accu- 

 mulated in the same way as the closely related and adjoining 

 drumlins. 



Had they originated as the terminal moraines of the retiring ice- 

 sheet, there seems to be no reason why they should so often exhibit 

 the peculiarities mentioned above. 



Were the heaping up of the gravel over rock mounds merely an. 

 accidental circumstance, and the mound but the remains of a once 

 continuous plain, we ought to find, in all cases in which it occurs, 

 the lowest false-bedding planes inclined at the highest angles, and 

 there should be a gradual approximation to horizontality in any 

 given bedding plane in proportion to its distance from the under- 

 lying rock ; instead of which, in all the examples that have hitherto 

 come under my notice, the principal false-bedding planes either 

 coincide in slope with that of the under-lying rock surface, or, more 

 usually, they exceed it in inclination. 



I am therefore inclined to think that the eskers originated in the 

 way I have suggested ; that is to say, that their position in the first 

 instance was determined by the mounds upon which they stand 

 having been high enough above the stronger currents of the sub- 

 glacial streams to allow of the occasional heaping up of sand and 

 shingle washed out of the accumulating till higher ujd the valley, or 

 carried down from the surface. As the ice wasted, the vast quantities 

 of water- worn material, continually melting out of its surface, would 

 be washed down the moulins and crevasses to the bottom, where, if 

 they descended upon mounds out of the reach of the levelling action 

 of the stronger parts of the sub-glacial streams, they would remain 

 nearly as at first thrown down ; whilst the detritus which fell into 

 the channels would speedily be swept away to lower levels, leaving 

 nothing but the bigger blocks to mark their former presence on the 

 spot. This process, long continued, would give rise in the end — as 

 the last touches would be given to their form as the ice-sbeet was 

 upon the point of vanishing — to those strange hummocky mounds, 

 the land-locked hollows in which have been so sore a puzzle to all 

 geologists who have looked thoughtfully into the matter. 



I cannot, therefore, avoid the conclusion that all, or nearly all, the 

 forms of drift with which I am acquainted, or have read of, save, 

 perhaps, some of the low level moraine beds, and the tiny moraines 

 of the few glaciers which came after the melting of the ice -sheet, 

 have originated in the course of long periods of time beneath the 

 ice-sheet in the way detailed above ; and the conclusion seems 

 equally inevitable that the organic remains entombed in the ice 

 would be left in the same way as were the accompanying stones, at 

 all elevations up to the highest points reached by the ice ; and that, 

 therefore, the presence of marine exuvias in stratified, or other drift, 

 at whatsoever elevation they may be found, does not in itself prove 

 that in Glacial or Post-Glacial times the places where they occur 

 were ever reached by tbe sea. 



