﻿1851.] 



TRIMMER ON ERRATICS OF CHESHIRE. 



207 



munication *, written in 1847, for the Memoirs of the Geological 

 Survey of Great Britain. From this paper, although not yet pub- 

 lished, I take the liberty of making the following extract : — 



" By the melting and fracture of the ice, the detritus would be de- 

 posited under a great variety of conditions. Here we should have 

 great heaps of Kimmeridge clay, containing many tons weight, shot 

 down by the side of equally large heaps of unmixed chalk. There 

 the two would be blended together in smaller masses. As the melt- 

 ing ice drifted about, much of this clay and chalk would be deposited 

 as separate fragments, water-worn by the wash of the sea over the ice. 

 The ice would have received part of the detritus in that state ; and 

 we should also find fragments buried in the mud, often retaining 

 scratches which their lower side had received when sliding, set in ice, 

 down the steep slopes of their native rocks, or which stranding ice- 

 floes had impressed on their upper surfaces when grinding over them 

 on the shore." 



The fragment of limestone, above re- 

 Fig. 3.— Outline of a ferred to, page 205, from the Till of 

 Boulder from the Till Manchester, is of the shape represented 

 of Manchester, bear- in fig. 3. The dimensions are, length of 

 ing scratches on most the side a 5| inches, of b 5|, of c 3 inches. 

 of its surfaces. Thickness of the side a 3 inches, thinning 



off on the sides c and d to 1^ and 1^ inch. 

 The face e and the opposite face are the 

 most polished and scratched ; the scratches 

 are inclined to one another at various 

 angles, which are greater on one face than 

 on the other. The faces at a and c are 

 slightly polished and scratched ; the face 

 at b is rough, without a scratch ; and that 

 at d rough, with a few scratches. 



The greater proportion of the specimens 

 of scratched detritus, sent to the Museum 

 from various localities by different observers, exhibit similar condi- 

 tions of form and of partial polishing and scratching on more than 

 one side. 



3. On the Sequence of Events during the Pleistocene 

 Period, as evinced by the Superficial Accumulations and 

 Surface-markings of North Wales. By Prof. A. C. Ram- 

 say, F.G.S. 



[The publication of this Paper is deferred, by permission of the Council.] 



* Quart. Journ. Geol. Soc. vol. vii. p. 20. 



