448 



TORTWORTH — GENERAL DESCRIPTION. 



Mr. Weaver 1 and that of MM. Buckland and Conybeare 2 . It was not, however, in the 

 power of any geologist at that day to describe correctly the order and succession of 

 the rocks, now called Silurian, from the diminutive and distorted features they dis- 

 play in this district. For although these rocks constitute a considerable portion of 

 the area around Tortworth, yet they are in many parts so ill exhibited, assume so 

 peculiar a mineral structure, and are in general so imperfectly divided into the forma- 

 tions composing the Silurian System, that it would be a hopeless task for any geologist, 

 even at the present day, who should here commence his observations on "Transition 

 Rocks," clearly to unravel their relations. Nature, indeed, has here presented us with 

 only an obscure miniature of those formations, the larger portraits of which must be 

 viewed in other districts. 



The Silurian rocks of Tortworth, it will be observed, lie in the direct prolongation of 

 those which we have traced from the valley of Woolhope in Herefordshire, through May 

 and Huntley Hills, and which, subsiding beneath the Old Red Sandstone at Flaxley, re- 

 appear on the right bank of the Severn at one point only, viz., Aram. On the left bank 

 they rise '■' en masse" at Purton passage, as represented in the foreground of the vi- 

 gnette p. 446, and expanding from that point stretch across by Berkeley, occupying this 

 part of Gloucestershire. 



Before, however, I proceed to describe these older rocks, I may, on this occasion, be 

 permitted to deviate from the method hitherto followed in this work, and give first a 

 general sketch of the structure of the whole tract, offering a few words upon each 

 of the overlying formations by which it is so remarkably diversified. To have repeatedly 

 carried the reader from other parts of the work to this small tract, whenever allusion 

 was made to any one of the numerous rocks of which it is composed, would have 

 prevented the attainment of a clear notion of its complicated structure. 



Taking the church of Tortworth as a centre, we see by the map, that this district is 

 made up of nearly every sedimentary deposit, from the Inferior Oolite to the Lower 

 Silurian rocks. The relations of all the strata, however, as might be expected in so 

 small a tract, are not clearly presented, still less the transitions from one group to 

 another. The very collocation of such a number of beds of different ages, within so cir- 

 cumscribed a space, is at once proof, that many of them must lie in abrupt and truncated 

 positions, which it requires some experience and considerable patience to detect and 

 explain. That such is the case at Tortworth, those who have perused either the memoir 

 of Mr. Weaver 1 , or that of Messrs. Buckland and Conybeare 2 , will be convinced; while 

 few modern observers can visit the spot without perceiving, that as rocks of igneous 

 origin have penetrated through it at many points, so they have doubtless largely con- 

 tributed to produce the disruptions and denudations which belong to the district. I 



1 Geological Transactions, vol. i. p. 317. 



Geological Transactions, vol. i. p. 210. 



