BOrLDER-CLAT OP CHESHIRE. 



593 



causes as that of some boulders of granite and trap to be alluded to 

 hereafter. 



When brick-making was in progress behind the Mission House in 

 Borough Road, Birkenhead, several blocks (five or six) of sand and clay 

 were exposed ; they contained a few erratic pebbles as well as 

 bauds, an inch or so thick, of vegetable mould. In one the claj^ey 

 and carbonaceous beds were doubled on themselves, being so bent 

 at the flexure as to squeeze away the clay. In this case also 

 the loose sand has fallen away and spread from the mass as it 

 settled down in the Boulder-clay. One piece exhibited spots of 

 carbonaceous matter, which are probably the rootlets of plants; 

 these are the only examples of vegetable life met with in the 

 Boulder-clay*. Being in close proximity to each other, they pro- 

 bably all dropped from the same iceberg stranded at this spot. The 

 only locality affording evidence of vegetation, in situ, during the 

 Glacial Period is at Leighton Hall, Tealand, Lancashire ; it occurs 

 as a band, ten or twelve inches thick, of Carboniferous-Limestone 

 pebbles, each of which is covered with an intensely black car- 

 bonaceous powder ; this bed separates a lower from an upper por- 

 tion of an accumulation forming a moraine mound, and indicates the 

 recession, for a series of years, of the glacier by which the mound 

 was formed. 



Blocks of the Boulder-clay itself, which would escape notice 

 should they occur in the Boulder-clay proper, in consequence of its 

 identity with them, have been frequently observed in those stratified 

 sands and gravels, previously referred to, which cover the bottoms 

 of preglacial valleys such as Happy YaUey (fig. 2) ; similar blocks 



Fig. 2. — Section in Happy Valley, BirJcenJiead. (Height 10 feet.) 



a. Trias. b. Sand. c. Gravel. 



e. Blocks of Boulder-clay in gravel and sand. 



d. Boulder-clay. 



* Mr. D. Mackintosh, F.G.S., found plant-remains in the Boulder-clay near 

 Crewe ; and Mr. T. Ward of ISi orthwich presented me with a fragment of wood 

 obtained at a depth of 35 feet in undisturbed Boulder-clay. 



2t2 



