460 A. R. Horwood—Origin of the British Trias. 
in their typical development’ yield neither coal-seams nor the flora 
and fauna which have been obtained on Clee Hill. Similar coals, 
however, occur elsewhere in England and Wales at intervals up to 
much higher horizons, though not in association with the typical 
Etruria Marl rock-facies. The objection based cn the flora is of 
greater weight, for Dr. Kidston finds that the plants are Middle 
Coal-measure forms, and therefore suggestive of a horizon lower than 
the Etruria Marls. But it may be remarked that the flora of the 
Blackband Group immediately below the Etruria Marls—the latter 
yield but rare plants—include no forms which do not occur in the 
Middle Coal-measures below.* The fauna of the marine bands is 
unfortunately of no horizonal value, though it includes a Productus 
which Dr. Vaughan finds closely resembles a form (P. aff. scabriculus, 
Mart.) abundant in the Avon section and elsewhere at the top of the 
Dibunophyllum Zone. 
Finally, a consideration of the thicknesses and characters of the 
sedimentary series and of the outcrops of dolerite shows that earth- 
movements along a N.E.-S.W. line have made themselves felt 
during— 
1. Upper Old Red Sandstone and Lower Carboniferous times. 
2. Some period between Lower Carboniferous and Coal-measure 
times. (The latter movement has resulted in the unconformity 
between the ‘Millstone Grit’ and the Coal-measures.) 
And further that the dolerite came up through several passages, 
some of which form a linear series having approximately this trend also. 
V1I.—Tase Oriein oF tHE Bririse Trias.® 
By A. R. Horwoop, 
Leicester Museum. 
S a result of an investigation covering the Midland area, and 
especially from a study of the Upper Keuper of Leicestershire, 
the author, who has been aided in this research by a grant from the 
Government Grant Committee of the Royal Society, has arrived at 
the conclusion that, in so far as Great Britain is concerned, the Trias 
was laid down under delta conditions, during which, as in the Nile 
area to-day, seolian action took place, but was not responsible for 
deposition except locally on a small scale, and following the prevalent 
wind course. 
The premises upon which this view is based are as follows :— 
1. There is a continuity of area of deposition during the Upper 
Carboniferous, Permian, and Triassic periods, and a relative homology 
between the different parts of each, i.e. the base of each is similarly 
coarser than the top, and each has a red phase ultimately. 
2. There is a gradual gradation from coarse sediments to finer from 
below upwards, as in modern (and other fossil) deltas. For instance, 
pebbles predominate in the lower phase, coarse sandstones (with 
See Dr. W. Gibson, Quart. Journ. Geol. Soc., vol. lvii, pp. 251 et sqq., 1901. 
Dr. R. Kidston, Quart. Journ. Geol. Soc., vol. lxi, p. 318, 1905. 
Abstract of paper read at the British Association, Sheffield, September, 1910. 
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