NORTH-WEST OF ENGLAND AND NORTH WALES. 123 



sands traceable to any thing similar to the grounding of ice in any 

 form, though they have rested on rock in immediate proximity to 

 a polished surface. As a rule, the Boulder-clay rests upon the sand 

 as if deposited in the most quiet manner. 



Gtjllt-Grayels. 



The ramifications of gullies below low-water mark which I have 

 described as existing in the substratum of rock beneath the Drift are 

 usually filled with rolled gravels. 



This is not invariably true, as, if deep, they sometimes contain 

 gravels and sands, or, as in the case of the valley of. the Mersey at 

 Widnes, clay. To some extent their presence may be dependent upon 

 the rate of inclination of the bed of the gully. The gravels are of 

 rocks similar to the stones found in the Drift. It is also not an un- 

 common occurrence to find gravel and shingle resting upon the rock 

 under the Boulder-clay*, or, more rarely, in patches within the lower 

 clay. It is readily conceivable that, if there was any tendency to the 

 accumulation of gravel on the sea-bottom, it is just at these gullies 

 kept clear by the rush of fresh water down them that we should 

 expect to find gravel and shingle. The invariably rolled character 

 of these stones seems to point to their accumulation at or near 

 "between tides." I have, however, never seen any arrangement of 

 the gravels that could be distinctly described as littoral ; probably 

 increasing submergence brought them under the influence of other 

 currents which disturbed what was originally a littoral arrangement. 



It is difficult to draw a distinct line of demarcation between these 

 gravels and the Drift above, as in some sections they alternate with 

 beds of sand and clay. At Hooton Station, Cheshire, there was a 

 great depth of them, and also at Eidlers Perry, near Warrington. 

 And lately a boring at Halewood, about | of a mile from Hunts Cross 

 station, and not far from my line of section of the Liverpool Extension 

 Railway (fig. 6, p. 90), showed a depth of 137 feet of Drift. The 

 surface-level was the 100 feet contour, the bottom bed being gravel 

 8 feet thick resting on Keuper Marl unbottomed at 417 feet. 



They underlie the Boulder-clay in the bed of the Mersey in many 

 cases where it has been exposed by dock- excavations, and often show 

 distinct signs of current-bedding. I see no reason to infer that these 

 gravels have been derived from any preexisting Boulder-clay. If 

 they had been, or if the Boulder-clays were remanies, some vestiges of 

 the original Till would surely have been before this discovered. I 

 have searched in vain for it. 



Low-level Boulder-clay and Sands. 



These represent by far the greatest bulk of the drift-deposits of 

 the north-west of England. It was to these beds that my attention 

 was at first more particularly directed ; and in Part 1. 1 have described 



* The excavations of the Atlantic Docks proved that these gi'avels lie in stream- 

 like patches on the rock (see plan of Docks, p. 86). 



