QUATERNARY DEPOSITS OF BRITISH ISLES — BROOKS. 319 



Very occasionally indications are found of a much older bowlder 

 clay separated from the later clays by a true interglacial period. J. 

 D. Kendall (89) gave particulars of a number of borings at Lindal 

 and Crossgates in Furness, in which a bed of vegetable matter 600 

 yards long by 300 yards wide was found between upper blue and 

 gray bowlder clay and lower red and gray bowlder clay. The red 

 color of the latter probably represents an old weathered surface. 

 There are a number of similar vegetable deposits in North Lan- 

 cashire and West Cumberland, which are referred by the author to 

 this horizon, though they are not both overlain and underlain by 

 bowlder clay. The flora of the peaty deposit, according to J. Bolton 

 and Miss E. Hodgson (90), consists of diatoms, mostly of local recent 

 species, with fern spores, Sphagnum and leaves and fruit of beech. 

 It is difficult to avoid the inference of its interglacial age. 



In eastern Ireland the succession is identical, and we have there 

 further evidence in the relations of the bowlder clay to the raised 

 beaches, that all three members of the tripartite series correspond 

 to the second glacial of England, or the Hessle clay, and similar 

 relations are suggested by the discovery at Egremont (91) of an old 

 sea cliff, indicating a level similar to the present, beneath the " lower 

 bowlder clay " of the tripartite series. 



It is difficult to make out the course of events in the period im- 

 mediately following the last general glaciation of northwest Eng- 

 land. Of later date are local moraines in the mountain valleys of 

 north Wales and Cumberland. They have not yet received any de- 

 tailed study, but B. Smith (92) remarked that there were splendid 

 terminal "moraines between 500 and 800 feet on Black Combe, in 

 Cumberland; these probably represent a snow line at about 1,100 

 feet. This would correlate them with the " large valley glaciers and 

 district ice sheets " of Scotland, which, I shall show, probably belong 

 to the concluding stages of the upper bowlder clay glaciation. No 

 later moraines have been described with a higher snow line, though 

 they probably exist in the highest mountains of Wales and Cum- 

 berland. 



The sequence of events on the coasts of Lancashire and Cheshire 

 after the formation of the upper bowlder clay is rather obscure. 

 During the melting of the ice the land apparently lay at first below 

 its present level, for the bowlder clay is covered in places by a bed of 

 reassorted gravel, T. M. Eeade (93). This was rapidly followed 

 by elevation, and the formation of river valleys below sea level, but 

 Mellard Eeade mentions no deposits which he attributes to this 

 stage. 



The next stage appears to have been a submergence to about 50 

 feet below the present level, corresponding to the 50-foot beach of 

 Scotland, to which Mellard Eeade and C. E. de Eance attribute a 



