TRANSACTIONS OF SECTION C. Soo 



twenty- three years ago — so well, indeed, that his address might serve as a text-book 

 on the geology of the district. In the following jear (1876) there appeared tin- 

 Survey Memoir on the Geology of East Somerset and the Bristol Coal-fields by 

 Mr. H. B. Woodward, who has since contributed important memoirs on the 

 Jurassic roclis of Britain, which are so largely develof^ied in Somerset and the 

 adjacent counties. Since that date many papers also have appeared in various 

 journals, and some of these, as might be expected, give new and perhaps more 

 accurate interpretations of phenomena previously described. In addition to this, 

 portions of the south-west of England have been geologically re-surveyed, and in 

 some cases new maps have been published. 



I would call especial attention to the Survey map on the scale of four miles to 

 the inch, known as the ' Index-map,' which has recently been issued. Sheet 11 in- 

 cludes this particular disti-ict : but if a portion of sheet 14 is tacked on to its southern 

 border we obtain a block of country about 120 miles square, which has not its 

 equal for variety of geological formation in any part of the world within the same 

 space. If Europe is to be regarded as presenting a geological epitome of our globe, 

 and if Great Britain is an epitome of Europe, then, without doubt, this particular 

 block of the south-west, which has Bath for its more exact centre, with a radius 

 (say) of fifty miles, may be said to contain almost everything to be found on the 

 geological scale, except the very oldest and the very youngest rocks ; while east of 

 the Severn and south of the Bristol Channel true Boulder clay is rai'e or absent. 



It may be convenient to consider a few points whicii have arisen of late years 

 in connection with the geology of portions of the district now under consideration. 



Pakeoxoic. — -If we omit the Silurian inlier at Tortworth, the geological history 

 of the country, more immediately round Bristol, may be said to commence with 

 the Old Red Sandstone, whose relations with the Devonian towards the south-west 

 have always presented some difficulty. And this difficulty is accentuated by 

 doubts as to the true Devonian sequence in West Somerset and North Devon. 

 Ever since the days of Jukes that region has been fruitful in what I must 

 continue to regard as heresy uniil the objectors have really established the points 

 for which they are contending. The uncertainty is to be regretted, since it is 

 through these beds of AVest Somerset that the system is to be made to fit in with 

 the several members of the Old Red Sandstone. 



There is a mystery underlying the great alluvial flats of Bridgewater which 

 aflects more than one formation ; so much so that one cannot avoid asking why 

 there should be Old Red Sandstone in the Mendips and Devonian in the Quantocks, 

 The line which separates the Old Red Sandstone of South Wales and the Mendips 

 from the West Somerset type of Devonian lies here concealed. I have already 

 suggested '■ that, if we regard the Old Red Sandstone of South Wales as an inshore 

 deposit over an area which was deluged with fresh water off the land, we can 

 believe that further out to sea, in a south-westerly direction, the conditions were 

 favourable for the development of a moderate amount of marine mollusca. This 

 view not only does away with the necessity for a barrier, but it also, in a general 

 sense, suggests a kind of gradation between the Old Red and Devonian deposits. 

 Mr. Ussher, whose practical acquaintance with this region dates from a long period, 

 stated a few years ago that, ' as far as Great Britain is concerned, the true connec- 

 tions of the Old Red Sandstone beds with their marine Devonian equivalents have 

 yet to be carefully worked out on the ground.'- I am not aware that further pro- 

 gress has been made in this direction. 



The Cdrboniferous Limestone of the Bristol area has attracted the attention of 

 so many distinguished geologists that its palaeontology and general features are 

 tolerably familiar. Of late years we owe some interesting petrographic details to 

 Mr. AVethered. The varying thickness of the Carboniferous Limestone and also 

 of the Millstone Grit in this part of England is noteworthy. If we follow the 

 Carboniferous Limestone in a south-westerly direction, across the mysterious 



' Trans. Deronsh. Assoc, vol. xxi. (1889), p. 4.5. 



''■ ' Prospects of obtaining Coal by Boring So'ith of the Mendips,' Proc. Som. Kat, 

 Soc. vol. xxxvi. (1891), pt. 2, p. 104. 



