Vol. 56.] THE BUNTER PEBBLE-BEDS OF THE MIDLANDS. 287 



17. The Bttnter Pebble-beds of the Midlands and the Source of 

 their Materials. By Prof. T. G. Bonnet, D.Sc, LL.D., F.K.S., 

 F.G.S. (Head February 21st, 1900.) 



[Plate XX.] 



Contents. Page 



I. Introductory 287 



II. Petrography of the Pebbles 288 



III. Transport of the Pebbles 295 



IV. Possible Sources of the Pebbles 296 



Map showing the Maximum Extent of the Trias in Britain 300 



I. Introductory. 



Until the summer of 1895 I spent at least a month in every year 

 in the immediate neighbourhood of the northern end of Cannock 

 Chase. In lb80 I published 1 a short note on the pebbles in the 

 Bunter Conglomerate, so largely developed on that moorland. 

 A second appeared in 1883, 2 and the subject was mentioned in my 

 address to Section C at the meeting of the British Association in 

 Birmingham in 1886. 3 In 1890 4 I replied briefly to certain 

 criticisms on the hypothesis which I had adopted in regard to the 

 origin and history of these pebbles. Besides this, I published in 

 1888 5 some observations on the action of rivers in forming pebbles, 

 the results of a journey planned with a view of obtaining the 

 necessary facts, 6 and in 1895 7 a note on the Budleigh Salterton 

 pebbles which I had examined for comparative purposes. Since 

 that year, when my close connexion with Staffordshire was broken, 

 the pressure of other work has kept me from putting together 

 information acquired after 1886, drawing up a summary of the 

 whole evidence, and pointing out its bearing on the hypotheses 

 which have been advanced as to the origin of the pebbles. 



Throughout my work, though it was rather desultory, I have 

 gathered facts for myself, and so shall not attempt to burden these 

 pages with an elaborate list of the ' literature of the subject.' 

 That prior to 1869 is enumerated in the memoir of the Geological 

 Survey on the Coal Measures, Permian, and Trias of the 

 Midland Counties (by Prof. Hull), which is full of valuable facts; 

 my own papers contain references to the few which I have had 

 to notice, and one or two others will be mentioned in the course 

 of this com mimical ion. I owe the idea which I have developed 

 to the above-named memoir (though its author has abandoned it, 



1 Geol. Mag. 1880, p. 404. 2 Ibid. 1883, p. 199. 



3 Eep. Brit. Apsoc. 188ti (Birmingham) p. 601. 



4 Geol. Mag. 1890. pp. 52 & 235. 5 Ibid. 1888, pp. 54 & 285. 



6 These observations have been continued when opportunity occurred in 

 later visits to the Alps. 7 Geol. Mag. 1895, p. 75. 



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