86 



T. M. BEADE ON THE DBJET-BEDS OE THE 



Pig. l. — Plan of Atlantic Doclcs, Liverpool, 1874-81. 



J I II II IU 



Branch Dock No. 3; and here the Boulder-clay was again exposed. In 

 the trench for the dock- wall parallel with the river-wall the surface 

 of the Boulder-clay was 16 feet below ordnance datum. The section 

 disclosed 9 feet of Boulder-clay, 3 feet of sand occasionally developing 

 into gravel, and then from 3 to 5 feet of Boulder-clay resting on red 

 sand and red "roach" rock. 



A Postglacial gully excavated in the Boulder-clay intersected 

 the dock ; and in this was the trunk of an oak tree, about 3 feet in 

 diameter, lying longitudinally in the gully, as if it had been washed 

 down it, at a level of about 22 feet below high water ; a layer of 

 recent silt covered the whole. 



In May 1876 further excavations showed below the silt a con- 

 siderable thickness of peaty matter full of drift timber, principally 

 oak and pine. In one place only, at the base of the peat, I observed 

 the stump of a tree rooted into sand resting upon the Boulder-clay. 



At various times between 1876 and 1878 I carefully examined 

 the excavations of the series of docks and graving-docks, extending 

 over an area of about 80 acres, and made record sections of the beds 

 disclosed : these I reproduce (figs. 2-5, p. 88), as they will serve to 

 explain the drift-geology better than any written description*. 



It must be understood that the beds are so irregular that another 

 observer coming at a time when a different face was exposed 

 would no doubt give a different representation of it. The sections 

 I give I considered typical ; and I vouch for their accuracy. 



Speaking generally, the same succession prevails as occurred in the 

 sections already described. In ascending order we have the red 

 rock of the Trias with the red sand and rubble covering it ; upon 



* I must here express my indebtedness to Mr. Gr. F. Lyster, the engineer to 

 the Mersey Docks and Harbour Board, for the facilities of inspection afforded 

 me and for much information given. 



