122 T. M. EEADE ON THE DE1FT-BEDS OE THE 



The existence of these riverine gorges in the solid rock so far below 

 the present level of the sea is as certain a proof of former elevation 

 as the marine beds on the top of Tryfaen are of depression. All 

 the surrounding facts lend force to and consolidate that conclu- 

 sion. If this be so, it is the more easy to understand the existence 

 of a snowfield on what are now plains little above the level of the 

 sea. 



If there ever existed this extension of ice from the mountain-centres 

 (for I have observed no facts to warrant in the slightest degree 

 the idea of a Scandinavian ice-sheet extending over our island), 

 it must have melted back and separated into local glaciers before 

 the drift-deposits I have described were laid down. During the 

 progress of the great submergence it is as clear to my mind as any 

 thing can be in so difficult a geological subject, that no ice-sheet 

 existed in any part of Lancashire that I have examined*. 



I have studiously confined these speculations well within the 

 boundary of personally ascertained facts. 



Bed Sand and Rubble debkis of the Trias. 



When the underlying rock is not planed and striated, it is usually 

 covered with broken rock and packed rubble, graduating into red 

 or yellow sand, according to the colour of the rock beneath. In no 

 case that I have seen (and I have devoted much attention to this point), 

 where the sand is undisturbed, does it contain any erratic pebbles 

 or stones, nothing more than a half-imbedded boulder. In some 

 cases a considerable amount of this sand is stratified and evidently 

 rearranged by sea-action ; and it then may contain both shell-frag- 

 ments and erratic stones. In the description of the section at Bootle- 

 Lane Station (Part I. p. 27), I have called this sand " Ground-mo- 

 raine equivalent of the Scotch Till." At the time it was written I 

 had not seen the Scotch Till, but have since had the good fortune to 

 see a section in the new Cartsdyke Dock, Greenock, of the " Till " 

 resting upon red sandstone of the Calciferous series, in which the red 

 sand and rubble is interposed between the rock and the Till in a 

 manner precisely similar to what occurs between our marine Boulder- 

 clay and the Triassic rocksf . 



That this formation is the product of land-ice, I think is the most 

 feasible supposition, though this explanation is not without its diffi- 

 culties, as the same sort of beds sometimes arise from subaerial 

 decay. But I cannot conceive how icebergs or field-ice alone could 

 have so universally polished the rocks of our Lancashire plains, seeing 

 that, if so, it must have been done on a sea-bottom covered with 

 Boulder-clay, sands, or gravel. Nor have I in one single instance 

 with the most careful search found any disturbance in these red 



* The late Mr. Clifton Ward has expressed views on the glaciation of the 

 Lake district, with the moderate character of which I am disposed to agree. (See 

 Q. J. G. S. vol. xxix. p. 422 and vol. xxxi. p. 152.) 



t This is described in my paper " On the glacial Beds of the Clyde and Forth " 

 (Proc. of Liverpool G*ol. Soc v Session 1879-80). 



