51 REPORT — ]87o. 



most extensive, both geographically and sectionally, a great portion of its thickness 

 heing yet entirely undeveloped. One of the features which will be remarked by 

 visitors coming from other parts of England is the number and chai-acter of the 

 Secondary formations by which the Radstock basin is overlain. Here and there, it 

 is true, Mesozoic rocks have been denuded ; but by far the greater portion of the 

 Coal-field is hidden beneath a covering of New Red Sandstone, Lias, and Inferior 

 Oolite, and many of the shafts have had to pass through all these formations before 

 the coal-seams were reached. 



A veiy slight change in the geological circumstances of the past would have left 

 us in entire ignorance of the existence of a Coal-field so far south as Bristol ; and this 

 reflection induces the hope that in other parts of our country (at present believed to 

 be without coal, or, if present, to lie at such a depth from the sui-facethat it cannot 

 be worked) it may yet be discovered at a moderate depth. 



Another feature of the Kadstock Coal Measiu-es is their great thickness, which 

 Mr. M'Mui-trie estimates at 8000 feet. From this we may infer that, however 

 limited the areain Somersetshire of which we have at present positive knowledge, 

 we are very far indeed from the edge of that infinitely more extensive area which 

 the Coal Pleasures of the south of England originally occupied, and within which 

 outlying basins may still be found. 



It is abundantly evident that the Bristol Coal-field was originally connected with 

 that of the Forest of Dean and South Wales, with which it has many characters in 

 common, although it differs in other respects. 



_ In all we find the same arrangement of the different strata, namely: — 1st, an upper 

 division of productive Coal Measures ; 2nd, a central mass of Pennant Sandstone ; 

 and, 3rd, beneath, a lower division of productive Coal JNIeasures resting upon, 4th, the 

 Millstone Grit. Hitherto it has been fomid impossible to correlate the seams of 

 coal ; but they present many points of general correspondence in the districts referred 

 to ; and the information obtained leads to the conclusion that their greatest sectional 

 development occurs between Radstock and Bristol, according to the follo^ving esti- 

 mate of the thickness of the strata, number of seams, and thickness of coal-seams : — 



Table II. — Strata and Coal-Seams. 



This great sectional thiclcness is attended, however, with serious disadvantages ; 

 for although, according to the Report of the Royal Coal Commission, the Bristol 

 Coal-field was estimated to contain 6104 millions' of tons of coal, a large portion of 

 It lies at an unworkable depth. Another physical feature of the district is the 

 thinness of many of the seams from which coal is at present obtained. 

 _ In many of the collieries seams of from 10 to 12 inches in thickness are exten- 

 sively worked, thus setting a good example of economy of one of our most precious 

 natural ])roductions to other parts of England, where veins of similar thickness are 

 left behind as worthless. 



Another feature of the Radstock Coal-basin is the extreme richness of its beds in 

 the fossil flora of the Coal Measures. The Pennant Sandstone and Lower Measures 

 yield few plants ; but the Upper divisions contain much finer specimens than I have 

 seen elsewhere ; and the fossil flora of Radstock preserved in Mr. M'Murtrie's 

 Museum is alone^ worth a journey to study and admire. The fossil ferns are in 

 great variety and beautifully preserved. The /Sit/i/lance, Lepidodendra, and other 



