NOTES AND QUERIES. 



115 



" Upon the gravel rest two or three feet of vegetable soil, over which is 

 strewn another bed of similar gravel, an inch or two only in thickness, and 

 over all, under the existing herbage, the quartzose and red sandstone peb- 

 bles of the (so-called) Northern Drift. Taking our stand at this point, and 

 scanning the vale with the eye of a geologist, we may readily trace the se- 

 quence of all the deposits of which the elements of the landscape around 

 us consist. We cannot doubt that the Lias upon which we stand once 

 stretched across what is now the channel of the Severn, and rested upon 

 the Red Sandstone, as corresponding beds do at present on the opposite 

 shore at Awre, near Poulton Court. Looking directly up the river, we 

 may see distinctly, with the aid of a glass, the same bed stretching away 

 in a corresponding direction at the Hock Crib, and we know that a few 

 miles beyond this lies Westbury Cliff, where the lowest beds of the Lias 

 rest upon the New Red marls ; and these being at Flaxley, unconformably 

 placed against the Upper Silurian rock, thrown up near Sir Martin 

 Crawley's schools, enable us to judge at what period the great disturbance 

 of the Protozoic formations in this neighbourhood took place. 



"All these, from the Mayhill Sandstone to the upper beds of the Carbo- 

 niferous system, had been placidly deposited in their due order in the 

 depths of a vast sea. 



"The section of the Forest Coal-field, in any direction shown upon the 

 maps of the Geological Survey, indicates no relative disturbance of its 

 component strata prior to that effected by the turning-up of its edges by 

 the protrusion of older rocks, which form the tracts which separate it from 

 the neighbouring coal-fields of Bristol and Glamorgan, the central portion 

 remaining comparatively undisturbed. The relations of the Secondary to 

 the Protozoic and eruptive rocks of the district are everywhere the same, 

 and the line of unconformity between them may be traced from the trap 

 boss at Tortworth, behind us, on the S.E., to the flanks of the Malvern 

 range, before us, on the N.W. Wherever first or last exerted, we know 

 that the cosmic force by which that great Sienitic mass was abruptly up- 

 lifted produced the contortions of the Silurian rocks around it, and the un- 

 dulations of those before us and under our feet ; passing hence, still up- 

 heaving Silurian strata through those of the Devonian age, and penetrating 

 these again at Tortworth with a mass of trap, it subsides from this point 

 under the Bristol coal-field, to produce effects analagous to those already 

 described around and beyond it. It is not our object to trace further the 

 development of this force and its consequences, but to bring more promi- 

 nently forward than they have hitherto been brought in the Transactions 

 of the Club, those geological features, easily accessible at many points in 

 this country, by which we ascertain, approximatively, the period at which 

 these commotions, to which we at present owe the diversity of its soil, and 

 scenery, and access to its mineral wealth, took place. In and around the 

 Porest we have precipitous escarpments of Carboniferous limestone and 

 shales, with those of older rocks, in such position as to prove how great 

 must have been the extent of their detritus, carried away we know not 

 whither. As the ancient detritic material of the lowest and most compact 

 strata — which would necessarily be the most recent, and the last exposed to 

 aqueous action — has left no trace of its existence here, we may reasonably 

 expect to discover any debris of the higher strata which once reposed upon 

 these. 



" We have no traces in the Porest area, for example, of the Magnesian 

 Limestone and its associated beds, which in other parts of England, and 

 upon the Continent, follow in regular series those of the Carboniferous 

 system ; yet we find at Bristol a Magnesian conglomerate, with the re- 



