332 



NEW EED SANDSTONE. 



[Ch. XXII 



CHAPTER XXII. 



TRIAS OR NEW RED SANDSTONE GROUF. 



Distinction between New and Old Red Sandstone — Between Upper and Lower 

 New Red — The Trias and its three divisions — Most largely developed in Ger- 

 many — Keuper and its fossils — Musclielkalk and fossils — Fossil plants of thp. 

 Bunter — Triassic group in England — Bone bed of Axmoutli and Aust — Red 

 Sandstone of Warwickshire and Cheshire — Footsteps of Gheirotherkim in Eng- 

 land and Germany — Osteology of the Lahyr'mthodon — Identification of this 

 Batrachian with the Cheirotherium — Triassic mammifer — Origin of Red Sand- 

 stone and Rock-salt — Hyjjothesis of saline volcanic exlialations — Theory of the 

 precipitation of salt from inland lakes or lagoons — Saltness of the Red Sea — 

 New Red Sandstone in the United States — Fossil footprints of birds and rep- 

 tiles in the Valley of the Connecticut — Antiquity of the Red Sandstone con- 

 taining them. 



Between tlie Lias and the Coal, or Carboniferous group, there is in- 

 terposed, in the midland and western counties of England, a great series 

 of red loams, shales, and sandstones, to which the name of the New 

 Ked Sandstone formation was first given, to distinguish it from other 

 shales and sandstones called the " Old Red" (c, fig. 423), often identical 

 in mineral character, which lie immediately beneath the coal (6). 



Fi?. 4-23. 



I. New red sandstone. 



&. Coal. 



G. Old red. 



The name of " Red Marl" has been incorrectly applied to the red clays 

 of this formation, as before explained (p. 13), for they are remarkably 

 free from calcareous matter. The absence, indeed, of carbonate of lime, 

 as well as the scarcity of organic remains, together with the bright red 

 color of most of the rocks of this group, causes a strong contrast between 

 it and the Jurassic formations before described. 



Before the distinctness of the fossil remains characterizing the upper 

 and lower part of the English New Red had been clearly recognized, it 

 was found convenient to have a common name for all the strata inter- 

 mediate in position between the Lias and Coal; and the term "Poi- 

 kilitic" was proposed by Messrs. Conybeare and Buckland,^ from crojxtXo^, 

 variegated^ some of the most characteristic strata of this group having 

 been called variegated by Werner, from their exhibiting spots and streaks 

 of light blue, green, and buff color, in a red base. 



* Buckland, Bridg. Treat, vol. ii. p. 38. 



