ORIGINAL ICE STRUCTURES IN SANDS 229 



alternate with several thin streaks of coarse sand, the latter seldom 

 exceeding an inch or two in thickness. These beds are inclined 

 at considerably more than the angle of repose under water, reach- 

 ing about 40 , and have undoubtedly been oversteepened, although 

 scarcely distorted. Traversing this series is a thin, nearly hori- 

 zontal bed of rather coarse sand, six feet long and one to three 

 inches thick. This sand is for the most part horizontally bedded, 

 but cross-bedding also occurs, showing that it is undoubtedly 

 water laid in its present position. The remarkable thing is that 

 the cross-streaks of the inclined series are continuous above and 

 below this horizontal streak or layer and are interrupted by it, 

 showing that the horizontal bed came in subsequent to deposition 

 and oversteepening. 



It is unquestionable that the beds above and below the hori- 

 zontal one were once continuous. Assuming them laid down, 

 frozen, and over-steepened as described above, it is postulated 

 that a horizontal crevice was formed in the frozen mass and melting 

 took place along it in the ice and that water currents of sufficient 

 force to carry and rearrange the sands were allowed to enter. 

 With the final thawing of the mass these delicate structures were 

 not destroyed and are still preserved in the unconsolidated sands. 



Other occurrences in the same deposit exhibit irregular mixtures 

 of fine and coarse sands in which the finer-grained areas seem to 

 represent a bed that has been broken into distinct blocks or has 

 been drawn out into odd irregular stringers. This gives certain 

 areas, several feet across, the appearance of a coarse breccia in 

 which the finer sand areas constitute the angular masses, while 

 the coarser sands fill up the interstitial spaces like a matrix. Again 

 there are places where the oversteepened layers are so closely 

 associated with others whose attitude is consistent with present 

 conditions that the whole group almost baffles explanation in 

 detail. 



In conclusion it may be worth noting that most of the structures 

 described and illustrated could not have been produced in these 

 sands in their present unconsolidated condition. The steeper 

 layers on the other hand could not have been originally deposited 

 in their present attitude. It is necessary to introduce some inter- 



