106 THE TRENTHAM GRAVEL BEDS. 



they diverge from, intersect, and unite with each other up- 

 wards and downwards, and are evidently deep-seated, being 

 due in all probability to a fault which runs at the foot of 

 the hill and brings in the Permian strata. 



With regard to the sandstones and gravels, there is no 

 regularity whatever in their arrangement. They come in, 

 go out, thicken, divide, reunite, become wedged within each 

 other, and assume other forms which, extending over even 

 this limited area excite one's curiosity as to the actual 

 character of the conditions under which they were depo- 

 sited. If we continue our examination closer and closer, 

 if we take up a handful of the sand, or peer amongst 

 the loosely-piled coarse pebbles, or the finer gravel, in the 

 wall of the quarry, we shall find that, with the excep- 

 tion of a little coating of siliceous or calcareous matter 

 and here and there incrustations of oxide of manganese 

 (which latter are, however, confined to well-defined lines), 

 the whole mass is singularly free from extraneous or 

 earthy substances a condition which indicates the absence 

 of mud-depositing rivers communicating with or flowing 

 into the old Bunter seas. 



The pebbles of which the gravel is composed are all 

 water-worn and well rounded, and consist of fragments of 

 a great variety of quartzose and siliceous rocks, and in- 

 clude (with others) agate, chalcedony, cornelian, jasper, 

 porphyry, syenite, Silurian sandstones, old conglomerates, 

 Carboniferous limestone and chert, Millstone grits, indurated 

 marls, and volcanic ash ; but it is remarkable that there 

 are no examples of true granitic, hornblendic, or schistose 

 rocks, or of rocks of less ancient age than Millstone 

 grit. The Silurian sandstones contain an interesting series 

 of fossils, consisting of Pentameras oblongus, P. lens, 



