I98 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the case with his paper on iso-diametric lines representing the distri- 

 bution of sedimentary strata as distinguished from calcareous strata 

 with reference to the Carboniferous rocks of Britain*, also his paper 

 upon the evidence of a ridge of Lower Carboniferous rocks crossing 

 the plain of Cheshire beneath the Trias &c.t Another and equally- 

 important communication was brought by him before the Society 

 " On the Thickness of the Carboniferous Rocks of the Pendle Eange 

 of Hills in Lancashire, illustrating the author's views regarding the 

 South-easterly Attenuation of the Carboniferous Sedimentary Strata 

 of the North of England "J. This was followed by another paper 

 entitled, " Observations on the Relative Ages of the leading Physical 

 Features and Lines of Elevation of the Carboniferous District of Lan- 

 cashire and Yorkshire" §. Prof. Hull again in 1876 still further 

 enriched the literature of the Carboniferous system through a valuable 

 and exhaustive paper " On the Upper Limits of the essentially Marine 

 Beds of the Carboniferous Group of the British Isles and adjoining 

 Continental Districts, with Suggestions for a fresh Classification 

 of the Carboniferous Series " ||. I consider these contributions of Mr. 

 Hull of the highest importance, as bearing upon theoretical geology, 

 and tending to excite us to closer research and broader views as to the 

 physical geography and distribution of life during the Carboniferous 

 period — certainly one of the most prolific during Palaeozoic times, 

 governed by the distribution of land and water or their relations one 

 to the other, under marine, estuarine, and freshwater conditions. 



The nature of sediments, whether physical (such as inorganic 

 sandstones, clays, and shales) or organic (as calcareous marine or 

 freshwater limestones and their relation to life during deposition), 

 has hardly received the attention it demands. Little has been 

 written relative to these since Dr. Bigsby, in his memorable papers 

 in 1858-59, entered into the history and nature of the sediments 

 laid down over the sea-bottoms, and the immediate relations of 

 animal life to the strata which the fossil remains now occupy. He 

 made comparisons of the State of New York and Wales for obvious 

 reasons. Bigsby showed, through his elaborate researches, that, 

 owing to a determinate law (with few exceptions), the accumulated 

 " sediments graduate into each other, clearly seen in Wales, Scan- 

 dinavia, Russia, and America " The change in sedimentation usually 

 takes place slowly and tranquilly, and the majority of life in the 

 uppermost or terminated section perishes, thus showing that destruc- 

 tion or change can take place without any marked disturbing force. 

 This is perhaps more manifest in the accumulation of the Carbonife- 

 rous strata throughout Britain than probably in any other formation. 

 The marked difference, yet, on the whole, agreement between the 

 Scotch and border formations, or the Calciferous Sandstone, north of 



* " On Iso-diametric Lines as means of representing the Distribution of 

 Sedimentary Clay and Sandy Strata as distinguished from Calcareous Strata, 

 with Special Reference to the Carboniferous Rocks of Britain." Quart. Journ. 

 Geol. Soc. vol. xviii. pp. 127-146 (1862). 



t Loc. cit. vol. xxix. p. 171. \ Loc. cit. vol. xxiv. p. 319. 



§ Loc. cit. vol. xxiv. p. 223 (1868). 



I Loc. cit. vol. xxxii. pp. 613-651 (1876). 



