102 



T. M. EEADE ON THE DKIFT-BEDS OE THE 



The same vertical arrangement, generally speaking, prevails ; that 

 is, the base of the sections often consists of a clay evidently consider- 

 ably mixed up with the grindings of the Triassic rocks beneath. 

 Rounded boulders are also more plentiful in the lower beds. I have 

 seen, however, no shingle or gravel beds at the base such as I have 

 described as occurring at the Atlantic Docks, Liverpool ; but then 

 there have been no excavations made that could disclose them, and 

 the actual base of the clay is seldom visible on the Dee estuary. 



Fibrous gypsum from the Keuper marl is often met with in the 

 Cheshire Boulder-clay. I have in my possession a large piece taken 

 out of the dock-excavations, Liverpool ; but it is not so plentiful in 

 Lancashire as in Cheshire. The contained stones in the estuaries of 

 the Mersey and Dee are practically the same in character. The 

 greater depths of Boulder-clay usually lie in the valleys. At Ford a 

 boring showed 83 feet to the rock. It is probable that there exists 

 a considerable thickness of Boulder-clay to the seaward of the penin- 

 sula of "Wirral. 



Towards Chester, as shown in the section of Upton sand-hole 

 (fig. 8) and the section of the West Cheshire Lines described at page 

 100, sand comes in in much greater force as a constituent of the 

 drift sections ; and as we proceed up the Dee and branch off into 

 the river Alyn we find very great deposits of stratified sand and 

 banks of shingle. 



It would thus appear that the drifts of the Dee basin as well as 

 those of the Mersey are intimately connected with the nature of the 

 strata through which the river runs, and the respective levels of its 

 course. Very little of the Dee is fed from the Keuper marls, which 

 accounts for the preponderance of sands and gravels in its basin — 

 excepting in the lower parts of the estuary, which could be fed as 

 readily from the Keuper Marls of the Mersey basin as the Mersey 

 itself, as I propose to show in my concluding remarks. 



Drift of the Basin of the Ribble. 



My observations of the drift of this basin are limited ; but as 

 Mr. C. E. De Ranee gives a very full account of them in his " Super- 

 ficial Geology of the Country adjoining the Coasts of South-west 

 Lancashire'' (Memoirs of the Geol. Survey), this is of the less import- 

 ance, and my aim is, as far as possible, not to repeat what others 

 have described. 



The following are from my notes : — 



A section disclosed by a side gully of the Ribble running up to 

 Pinfold by Fiswick Kail showed stratified sand with beds of very fine 

 gravelly sand containing very rotten shell-fragments. A bed of 

 Boulder-clay lay against this bank, having a junction almost vertical ; 

 but it may have occurred from a land-slip letting down an overlying 

 clay. 



At Bezza Brook we see the red shaly rock at the base and many 

 boulders and erratics in the bed of the brook. A section of the drift, 

 about 8 feet deep, is disclosed, consisting of, first, mixed blue clay 

 and gravel lying on the shale, then Boulder-clay with gravel, and 



