44 Murchisoris Silurian System. 



and Caradoc ridge, these sandstones where not obscured by coarse 

 drifted gravel, are soft thick bedded building stones, usually lying in 

 slightly inclined strata. In a quarry at Condover, about thirty feet of 

 these beds dipping very slightly to the north-east, are arranged in the 

 following descending order. — 



1. Gravel; 2. Thin-bedded Sandstone; 3. Red, argillaceous Marl; 

 4. Sandstone ; 5. Argillaceous Marl as above ; 6. Sandstone ; 7. Marls as 

 above ; 8. Thick bedded Sandstone." 



Numerous other details are given from various districts 

 showing the connection of the lower beds of New Sandstone 

 with the coal measures and the older rocks ; frequent impres- 

 sions and fragments of coal plants have been discovered in 

 the beds which form a covering to coal-bearing strata; many 

 of the impressions of plants are in an imperfect condition, but 

 Professor Lindley had no hesitation in referring them to the 

 carboniferous epoch. In coal-fields the junction of the New 

 Red Sandstone with the coal-bearing strata is often obscured 

 by superficial detritus, but where the rock is laid open it is 

 sometimes a dark red, soft, thin-bedded sandstone, made up 

 of black and white grains, in a thin paste, with a few harder 

 concretions and some blotches of red marl ; at other times it 

 is harder, more siliceous, and intractable. Sometimes the 

 dolomitic conglomerate, the red sandstone, and the coal 

 beneath it are found resting upon the inclined edges of the 

 Silurian rocks. In the western extremity of Shropshire 

 the lower new red sandstone is directly superposed to the 

 coal measures and the new pits at Drillt, to the east of Os- 

 westry red sandstone marl and shale have been penetrated 

 to a depth of 100 yards before the first traces of coal mea- 

 sures were perceived, when after passing through several 

 layers of impure carbonaceous matter the usual coal seams 

 of the Oswestry field were reached, and are now largely 

 worked. 



The following is a recapitulation of the different groups 

 composing the New Red System in the districts examined 

 by Mr. Murchison. 



1 . Saliferous and gypseous marls with beds of sandstone. 



