22 2 NEW RED SANDSTONE. 



In the Rhretic Beds we have the earliest British Mammal, the 

 Jl/icroles/es, and in these passage-beds we leave the comparatively 

 barren New Red Rocks, and reach the commencement of the 

 highly fossiliferous strata which characterize the Jurassic system. 



The upper portions of the Triassic rocks (Keuper) are charac- 

 terized by the occurrence in them of Rock-salt and Gypsum ; and 

 these rocks were evidently deposited in a large and irregular lake 

 or lagoon, whose margin can in places be traced, although the 

 greater part of it has been destroyed. 



In certain localities the lower Triassic rocks contain pebbles of 

 hard quartzites, etc., which suggest the action of more powerful 

 waters than those of a lake. At the same time the red colour of these 

 rocks, due to a pellicle of peroxide of iron coating the sand-grains, 

 has been considered a proof that they were not laid down under the 

 sea. It is possible that the pebbles may, in some instances, have been 

 derived from old conglomerates, while from their local occurrence 

 they may have been accumulated as delta deposits, the production 

 of rivers draining the land-areas of the Triassic period.^ 



Regarding the Triassic rocks, however, as in the main of 

 lacustrine origin, we may conclude that the sediment was in part 

 brought down by rivers, and in part due to disintegration of 

 bordering cliffs or islets, which would account for some of the huge 

 blocks of porphyry and other rocks met with in the Trias of South 

 Devon, and which Mr. Godwin-Austen attributed to the agency of 

 moving ice. The same authority remarked on the glacial 

 conditions under which the materials of the " Red Conglomerate " 

 near Porlock were brought together.* (See sequel.) The rivers, 

 too, which at first may have been rapid and torrential, would, by 

 subsidence of the area, lose much of their transporting power and 

 bring down only the finer sediment. 



Bunter. 



The red sandstones overlying the Magnesian Limestone series 

 were identified in 1826 by Sedgwick with the Bunter (variegated) 

 Sandstone of Germany, a formation so-named by Werner. 



The general divisions of the Bunter beds are as follows : — 



[//per Red and Mottled Sandstone. — Soft, bright-red, yellow, white, and 



variegated sand and sandstone.^ 

 Pebble Beds or Conglomerate. — Harder reddish-brown sandstones, with 



quartzite pebbles, passing into conglomerate ; with sometimes a base 



of calcareous breccia. 

 Lo7ver Red and Mottled Sandstone.— 'io{i,\ix\'^^-x&d^, yellow, and striped or 



variegated sandstone, showing much false bedding ; with subordinate 



breccias. 



1 T. G. Bonney, G. Mag. 1880, p. 407 ; A. Strahan, Geology of Cheshire, 

 Iron and Steel Institute, 1885. 



2 Q. J. vi. 96, xxii. 2 ; see also W. Whitaker, Q.J. xxv. 157; and H. B. W. 

 Q. J. xxxii. 235. 



3 For remarks on variegated Bunter beds, see G. Maw, Q. J. xxiv. 363. 



