8o • 



beds and that the normal form of the cavities in clays, 

 • sands and gravels is that of troughs and furrows," then 

 " for the sake of a name I shall call the materials which 

 fill these furrows the Trail." This transported or re- 

 arranged material he says produced warp, and the 

 trail was the product of glaciation of the surface and 

 belonged to " one " period.* 



In this paper the word " Warp " will be qualified as 

 rain-warp or rainwash, to distinguish it from true warp or 

 the settlement from troubled waters. 



" Trail" is the material filling troughs and hollows, a 

 substance dissociated wholly from the beds whence it was 

 derived. Underplight,'\ is the term I shall . use for the 

 rocks and beds forming the folds and sides of the hollows, 

 which have been pinched, crumpled, and squeezed, into 

 sheets and ribbons, sometimes projecting into the trail but 

 still united to the parent rock from which they are in pro- 

 cess of separation, and to which they still obviously belong. 

 The .various minor curves, distortions and puddlings of 

 the stratified beds beneath are included in this " tender- 

 plight." It is necessary to make this distinction because of 

 the importance of distinguishing the position of fossils and 

 flint implements, whether they fell down into the glacial 

 mud or were squeezed up into it from below. 



Thus, Underplight is the result of the mechanical 

 movement of ice or thawing soil over the land. 



Trail is the re-arrangement of the detached and 

 comminuted rocks after the thawing of the ice. 



Rain-warp or older rain-wash is the finer stuff 

 separated from the trail, leaving the coarser part behind 

 as surface gravel. J 



* See Rev. O. Fisher, Q. J. Geological Soc. 1866. Geol. Mag. 

 1866, &c., &c., also a leUer in Nature, July 5, 1877, &c. 



I am greatly indebted to Mr. Fisher in this study, but I was 

 originally induced to examine the subject by Mr. J. Trimmer's remarks. 



t Plight, pleat, a folded condition. 



X The discovery of stones by the abstraction of the enveloping sand 

 and clay, is the cause of the popular notion that " Stones grow," an 



