26 S. S. Buckman — The Toarcian of Brcdon Hill. 



exactly what Ammonite faunas are found in the sands of Somerset 

 and Dorset, about which nothing precise was known a few years ago. 

 It is my discovery that the Sands and Cephalopod Bed contain some 

 half-dozen distinct Ammonite faunas, which maintain always the same 

 sequence, now proved widely on the Continent. By this sequence 

 I can date the different sands with precision, as I have done in 

 p. 456 op. cit. This is largely against Wright's " discovery." He 

 claimed all the sands as Lias. I am able, taking the arbitrary line 

 which Wright himself accepted, to show that certain of " these 

 various sands " are Lias, and others Oolite. I can claim to have 

 settled the much-debated question, because I have been able to give 

 the facts — the faunal sequence. 



Professor Hull asks where I "got hold of the idea" about the 

 comparative thickness of the Upper Lias at Wotton and Bredon. 

 Not from Survey publications, he is positive. I quote from " Geol. 

 Country around Cheltenham" (Mem. Geol. Surv., 1857, pp. 24, 25) : 

 " The Upper Lias Shale ... at Leckhampton Hill . . . 

 is 230 feet [in thickness] ... At Cleave Cloud ... 300 

 . . . At Bredon Hill . . . 100 feet or more . . . 

 Towards the south ... it thins gradually away to Wotton- 

 under-Edge, where it is about 10 feet thick." In Sheet 44, 

 Geological Survey, the outcrop of Upper Lias is 300 feet, measured 

 by the contour-map of the Ordnance Survey. H. B. Woodward 

 says : " In Gloucestershire the Upper Lias varies from about 

 10 feet at Wotton-under-Edge, to about .... 380 feet at 

 Bredon Hill." ^ 



Professor Hull asserts that he knew "the sands [G4] of Wotton 

 with the clays below [G3] were representative in time of the Upper 

 Lias [G 3] of Bredon Hill." If this was his opinion, why did he 

 not record it in his map ? If the value of G 3 changes from place 

 to place, it is not consistent mapping. If G 3 means G 3 at some 

 localities, and G 3-|-G4 at others, who is able to interpret the map? 



A plea put forward during the discussion of my paper tried to 

 justify the changing value of a symbol on the ground that it was 

 the object of the Survey maps to record lithology for the guidance 

 of agriculturalists. This seems to imply that the Survey maps were 

 not intended to be geological documents, but merely charts showing 

 the outcrop of the various clays, sands, or limestones. And if the 

 benefit of agriculturalists was so much considered, why were the 

 Vales of Evesham and Gloucester mapped as Lower Lias Clay, when 

 nearly their whole surface is thickly covered with sands or gravels? 

 What use is such a map to agriculturalists? I said that, for their 

 good, the superficial deposits should have been mapped first. Pro- 

 fessor Hull derides this idea : he implies that so much would be 

 blank. He forgets that, in the few places where the solid rocks 

 are not marked by technical ' drift,' from the farmers' and from 

 a strictly scientific point of view the soil and subsoil are superficial 

 deposits, whose varying phases are quite as capable of being mapped 

 as anything else. There need have been no blanks. 



1 " Geolog-y of Eiiglaud and Wales," 2nd ed., p. 276. 



