pARBONIFEROT 103 



south in the character of their sandstones and 

 ironstones, and they yield, in various localities, 

 some thin beds of coal. 



In Scotland this third division ui the car- 

 boniferous group of rocks, is named the Moor 



k. Its only difference from the Millstone 

 Grit, is in containing marine fossils. But this 

 condition probably only indicates that the lacus- 

 trine basins, in which much of the deposit may 

 have been formed, were sometimes o\)l'\\ to the 

 sea. Southward in England, the Moor rock 

 known as the Millstone grit, consists chiefly of 

 alternations of sandstone and shale. It is only 



50 feet thick in Leicestershire but thickens in the 

 West. In Northumberland it is 400 feet thirk. In 

 the Forest of Dean it is less than 500 feet. It is 

 1000 feet thick in the Somersetshire coal held. 



:n this deposit a large part of the flagstones 

 of Britain is obtained. It forms the wildest scen- 



of the western side of the Pennine chain. This 

 is due to tic the four principal beds 



of grit which rest upon each other in successive 

 terraces, with the thick Kmderscoiit grit at the 

 bottom, and the three less important grits above, 

 which are all divided from each other by shales 

 and sand St re many thin beds of 



coal in the Millstone (irit. None of them art- 

 worth working, so that the coal miner knows the 

 deposit in England as the Farewell rock, below 



which coal is not to be expected. The existence 

 of the Millstone (irit indicates an upheaval of 



the Carboniferous Limestone sea, by which the 

 conditions of physical geography became simi- 

 lar in England to what they were in Seo.land. 

 Such an upheaval exposed the uplifted rocks to 

 denudation, and probably furnished the material 



