NORTH-WEST OF ENGLAND AND NOBTft WALES. 87 



this lies the shingle or gravel ; but sometimes the Boulder-clay lies 

 directly on the rock, and in other cases the shingle is divided by 

 patches of Boulder-clay. At another point the gravel is entered 

 by a sand seam which divides the Boulder-clay where the deposit 

 becomes thicker in consequence of depressions in the surface of the 

 rock on which it rests. 



The lower part of the clay may be described as containing more 

 waterworn boulders than the upper, thus partaking of the nature of 

 the shingle it is in contact with. The upper part of the clay is more 

 plastic, like that of the Huskisson Branch Dock, but contains, usually, 

 large and numerous glaciated erratics of granite, dolerite, diorite, 

 limestone &c, some of which must weigh several tons. 



In November 1881 I made a very careful inspection of the exca- 

 vations then going on in Dock F, the most northern of the series : 

 in this I was assisted by Mr. John Dickson, the contractors' engineer, 

 who has had charge of all the excavations from the commencement. 

 The sections are shown on p. 88. A-B (fig. 2) shows the face of the 

 cutting of the south side of the dock, C-D (fig. 3) that on the north 

 side ; they are seen in reverse directions. This dock over its whole 

 area showed a much more decided and persistent arrangement of the 

 beds than did any of the others. Commencing at the base, in section 

 A-B, we have, in ascending order, ISTo. 1, a bed of gravel and sand not 

 bottomed, 5 feet ; jSTo. 2, a bed of short hard clay containing many 

 waterworn drift stones. This clay contains shell-fragments, and in 

 excavating requires to be first loosened with the pick. jSTo. 3, a bed 

 of sand varying in thickness from 2 or 3 feet to a mere line. It is 

 remarkably persistent all over the dock ; it appears to be a line of 

 erosion running nearly in one plane with a slight dip towards the 

 river, excepting in places where it curves into hummocks, as shown 

 in section C-D (fig. 3), where it in one place develops into gravel, 

 and at another is split up by a tongue of clay. 



No. 4, strong plastic clay which has to be got with the grafting- 

 spade, consequently costing more labour in the getting. It contains 

 many erratic boulders, principally of diorite, the largest measuring 

 •1 ft. 6 in. by 4 ft. 6 in", by 4 ft. 6 in. I counted thirteen lying at 

 the S.E. corner of the dock. It is about 13 feet thick at the east 

 end, but thins down to about 7 feet at the west end of the dock. 

 Bricks are made from this clay for use in the dock-works. The 

 clay Xo. 2 is unfitted for brickmaking. 



2no 5 is a Postglacial silt, in which many bones of Cetaceans have 

 been found, also red deers' antlers, skulls and bones of a small variety 

 of horse &c. They usually lie near the base, which rests on the 

 Boulder-clay. 



As these last sections were decidedly the most markedly stratified, 

 it was of importance to find out if any distinctions occurred in the 

 organic remains which they contained. This could not very well 

 be done through evidence of the Mollusca, their remains, though 

 present, being scattered and fragmentary, and no heaps of clay being 

 left from which weathering would separate them, as happens in 

 brick-fields. I therefore submitted, for microscopic examination 



