On the Glaciation of South Lancashire, Cheshire, Sfn. 75 



The Chanter's-Seat conglomerate contained many grains of quartz 

 and felspar, curiously like those minerals in the so-called Dimetian, 

 together with numerous small rolled fragments, about a quarter of 

 an inch in diameter, exactly resembling the finer-grained varieties 

 of that rock, besides bits of felsite, similar to some which occur in 

 the St. David's district, quartzite, a quartz-schist, and an argillite. 



The rocks in situ in the Trefgarn quarry were indurated trachytic 

 ashes, together with the curious flinty rock which was the most 

 typical of the so-called halleflintas. One of the pebbles from the 

 overlying conglomerate perfectly corresponded with the last-named 

 rock, others appeared to be most probably from an altered trachytic 

 ash, differing only varietally from those in situ. 



After prolonged examination of this " halleflinta" of Trefgarn 

 and the similar rocks from Roch, he was of opinion that while it was 

 possible that some specimens might be altered ashes, most of them 

 were originally rhyolites or obsidians, devi trifled, and then silicified 

 by the passage of water which had contained silica in solution. 

 The Trefgarn group obviously could not be intrusive in the lower 

 Cambrian, and it was extremely improbable that the Eoch Castle 

 series was newer than the basement conglomerate of that district. 



The Brawdy granitoid rock might be a granite, but at any rate it 

 presented considerable resemblance to the " Dimetian'." 



It was therefore evident that the Cambrian conglomerate of St. 

 David's was formed from a very varied series of rocks, some of them 

 much older than it, and that the Dimetian could not be intrusive in 

 it. Moreover, even if the Dimetian should be proved ultimately to 

 be a granite, and the core of a volcano which had emitted the rhyo- 

 lites, sufficient time must have elapsed after its consolidation and 

 prior to the making of the conglomerate to remove, by denudation, 

 a great mass of overlying rock. Hence, whatever its nature, it was 

 pre-Cambrian. 



3. "On the Glaciation of South Lancashire, Cheshire, and the 

 Welsh Border." By Aubrey Strahan, Esq., M.A., F.G.S., H.M. 

 Geological Survey. By permission of the Director General. 



Part I. South Lancashire and Cheshire. 

 The average direction of the large number of glacial striae which 

 have been observed in the neighbourhood of Liverpool is N. 28° W. 

 Further up the Mersey there is a slight deflection towards the east. 

 Two instances only occur of striae having a totally different direction, 

 namely E.N.E. The striae themselves seldom furnish any evidence 

 as to the direction in which the ice travelled, but the edges of the 

 strata have in many cases been bent back from the north-west. 

 The materials of which the drift is composed, both matrix and 

 included boulders, have also travelled from the north-west. The 

 sands and gravels also are arranged in long banks, trailing away 

 from the south-west sides of the rock-hills, in such a way as to 

 show that they are distributed by currents from the north-west. 

 The striae are found in connexion with the Boulder-clays, in which 

 the actual presence of ice is abundantly proved. Presumably the 



