1872.] SOLLAS AND JUKES-BROWN — INCLUDED EOCK-EBAGMENTS. 13 



schists, granites, vein-quartz, grits, quartzites, and slates are very 

 numerous. 



We may form the following generalizations from the characters 

 which these stones present. 



I. Most of them are subangular, and many are extremely 

 friable. The presence of these latter rocks is remarkable ; fragments 

 of soft sandstone (No. 3, for example), of various shales and talcose 

 schists, are frequently met with, which could never have borne even 

 a brief journey by water along the ocean-bed. 



II. Many of them are of large size, especially as compared with 

 the fine silt in which they were imbedded, the larger ones mea- 

 suring more than a cubic foot. It is obviously impossible that any 

 ordinary marine current could have moved along such blocks as 

 these, especially from such great distances as we shall show they 

 have probably come. 



III. They are of very various lithological characters, and de- 

 rived from several Palaeozoic formations ; among the most abun- 

 dant are mica-schists, basalts, granites, felspathic shales, vein- 

 quartz, and coarse grits ; and we may refer them to gneissic, 

 schistose, volcanic, and sedimentary rocks, probably of Silurian, 

 Old-Red-Sandstone, and Carboniferous age. Such strata are not 

 found anywhere in situ in the neighbourhood ; and we must go to 

 a great distance before we find any at all corresponding to them, 

 either to Scotland or to Wales. This consideration, that numerous 

 rock-fragments, some of which are very friable, have been brought 

 from various localities at great distances, and yet retain their 

 angularity, seems to us almost sufficient evidence in itself for their 

 transportation by ice. We dismiss, at once, all notion of the agency 

 of trees ; for it is scarcely conceivable that so many stones from 

 so many different formations could have been repeatedly borne to 

 sea by such exceptional means of transport. The majority of these 

 erratics present no signs of ice-scratches ; but when we reflect on 

 the small proportion of ice-scratched stones in the moraine matter 

 borne away by an ordinary iceberg, and on the small percentage 

 of ice-scratched boulders in many deposits of recent glacial drift, 

 we see nothing in this fact inconsistent with their glacial deri- 

 vation, especially when we remember that many of our Upper 

 Greensand boulders are composed of soft or decomposable rocks 

 from which ice-marks, even if once existing, would probably have 

 been erased by the subsequent action of water. We think, there- 

 fore, that even without any more positive evidence we should have 

 in this assemblage of large rock-fragments, mostly subangular 

 and derived from various and distant formations, great reason to 

 attribute their occurrence in their present situation to the trans- 

 porting power of ice. Some of the stones present a few scratches 

 in different parts of their surface, which are difficult to account for, 

 except by the agency of ice ; and others have flat faces which look as if 

 they had once been striated surfaces. The stone numbered 8, espe- 

 cially, which is preserved in the Woodwardian Museum, we find 

 to be unmistakably scratched in various directions, the striae 



