Dr. Alexander Irving — The Trias of Devonshire. 167 



Professor Hull, F.R.S., and myself among the Eed Kocks of the 

 South Devon coast, with especial reference to " the Base of the 

 Keuper in South Devon." I desire to reply here to Mr. Somervail, 

 and in so doing shall have to refer frequently to the three papers 

 of my own published in the Quarterly Journal of the Geological 

 Society in the years 1888, 1892, 1893, and to the paper by 

 Professor Hull in the same Journal in the year 1892. For the sake 

 of convenience and brevity I will refer to these papers by certain 

 letters, as below.^ 



Mr. Somervail states (p. 460) : " There is only one point in which 

 I differ from these authors ; it is in relation to the rocks forming the 

 base of the Keuper in this area." He states further that " in the 

 last of these papers both authors agree to regard certain breccias 

 occurring at the mouth of the river Otter, and again at the mouth 

 of the Sid on its eastern side, as the basement beds of the Keuper." 

 This is not quite an accurate statement, seeing that the base of the 

 Keuper along the Otter Valley was definitely worked out by me 

 after Professor Hull's paper (H) was published, and the results 

 given in paper C a year later. In the discussion which followed the 

 reading of paper G at the Geological Society Professor Hull repeated 

 his assent to my reading of the district so far as the basement-line 

 of the Keuper was concerned ; and at the same time gave up his 

 previous contention that the great marl series of the district further 

 west, and below the Budleigh Salterton Pebble-bed, was the 

 representative in the Devon area of the Lower Bunter of the 

 Midlands and the Severn country. - 



Mr. Somervail tells us that I have described the breccias near 

 the mouth of the Otter " as calcareous or dolomitic breccias or 

 conglomerates." Here there are two slight inaccuracies ; for (1) 



1 (A) A. Irving, "The Eed Eocks of the Devou Coast- Section " : Q.J.G.S., 



vol. xliv (May, 1888). 



(B) " Supplementary Note on the Eed Eocks of the Devon Coast- 

 Section" : Q.J.G.S., vol. xlviii (Feb. 1892). 



(C) "The Base of the Keuper Formation in Devon": Q.J.G.S., 



vol. xlix (Feb. 1893). ■ 



(H) E. Hull, F.E.S., "A Comparison of the Eed Eocks of the South Devon 

 Coast with those of the Midland and "Western Counties": Q.J.G.S., 

 vol. xlviii (Feb. 1892). 



2 In a letter to me afterwards Professor Hull went even further, and declared 

 himself inclined to view, in the light of these later facts, all the so-called Lower 

 Bunter of the Midlands as more closely related to the Permian than the Trias. For 

 my part, I should, in the light of my work in Central Germany in 1883 (see Q.J.G.S. 

 for August, 1884), hesitate to go so far as that. It would tend to drag us back into 

 the Murchisonian confusion of thought, arising from insufficiency of observation, 

 which it was the definite purpose of that paper (and of one supplementary to_ it in 

 the Geol. Mag. of that year) to clear away. My contention was, andis, simply 

 that the marl series of Devon are the equivalents of the identically similar marls, 

 wMch are interbedded \xiVa. the Magnesian Limestone beds of the Permian in the 

 regions to the east of the Pennine Chain, and conspicuously so in Notts ; and that 

 the Lower Bunter of the Midlands is wanting in the basin south of the Mendip Axis, 

 even as Professor Hull, in his work on "The Permian and Triassic Eocks of the 

 Midland Counties," has shown it to be wanting in various successions in the Severn 

 country, to which references are given in my papers. See fiu'ther my paper 

 "Twenty Years' Work at the Younger Eed Eocks" (Geol. Mag., August, 1894); 



