PART 11. CHAPTER XIX. 



235 



New Red Sandstone. 



land, until we reach the great plain of Lias at the base of the 

 Inferior Oohte at Metz. 



It is evident, therefore, that the denuding causes have acted 

 similarly over an area several hundred miles in diameter, sweep- 

 ing away the softer clays more extensively than the limestones, 

 and undermining these last so as to cause them to form steep 

 cliffs wherever the harder calcareous rock was based upon a 

 more yielding and destructible clay. This denudation probably 

 occurred while the land was slowly rising out of the sea.* 



CHAPTER XIX. 



NEW RED SANDSTONE GROUP. 



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

 New Red — Muschelkalk in Germany — Fossil plants and shells of New Red 

 Group, entirely different from Lias and Magnesian limestone — Lower New Red 

 and Magnesian limestone — Zechstein in Germany of the same age — General 

 resemblance between the organic remains of the Magnesian limestone and Car- 

 boniferous strata — Origin of red sandstone and red marl. 



Between the Lias and the Coal, or Carboniferous group, 

 there is interposed in the midland and western counties of Eng- 

 land a great series of red marls and sandstones, to which the 

 name of the New Red Sandstone formation was given, to dis- 

 tinguish it from the other marls and sandstones called the " Old 

 Red," (c. Fig. 232.) often identical in mineral character, which 

 lie immediately beneath the coal, h. 



Fig. 232. 



Old Red. Coal. New Red sandstone. 



In some parts of the south-west of England, the entire " New 

 Red" group consists exclusively of red loam, clay, and sand- 

 stone, devoid of fossils, strongly contrasted in colour, and the 

 general absence of calcareous matter, with the Oolitic rocks and 



* See Principles of Geology, Index, Wealden denudation. 



