A HISTORY OF DERBYSHIRE 



and also for ornamental purposes, though the introduction of iron mantel- 

 pieces has greatly reduced the output of encrinital marble previously 

 used. The various grits and sandstones are used for buildings and 

 millstones, the clays for making bricks, and the Bunter sandstone for 

 moulding. The Keuper marl supplies gypsum and alabaster for making 

 plaster of Paris ornaments and rock work, and calcareous tufa is largely 

 quarried for grottoes. 



The following table gives a list of the strata found in Derbyshire : 



TABLE OF STRATA 



Quarternary 



or 

 Port Tertiary 



Secondary 



or 

 Mesozoic 



Recent 



Pleistocene 



Triassic 



Keuper . 

 Bunter , 



Alluvium, peat bogs, calcareous 

 tufa, stalactitic formations 



Cavern deposits, glacial drift, 

 boulders, sands and clays 



/Red marl, with gypsum 



\Waterstones 



/Pebble beds or conglomerate 



\Lower mottled sandstone 



Permian 



Magnesian Limestone 

 Series 



Marls and sandstones 

 Lower magnesian limestone 

 Marls and sandstones 



Coal Measures 



Millstone Grit 



Primary 



or 

 Palseozoic 



Carboniferous 



Yoredale Rocks , 



Mountain Limestone 



Middle coal measures 

 Lower or Gannister series 



1. Rough rock 

 Shales 



2. Sandstone and shales 

 Shales 



3. Chatsworth grit 

 Shales 



4. Kinder Scout grit 

 Shales 



5. Shale grit 



Shales, with thin sandstones 

 Shales, with thin beds and nodules 

 of earthy limestones and con- 

 temporaneous volcanic rocks 

 (Limestone, with chert, thin shales 

 and clay partings and contempo- 

 raneous and intrusive igneous 

 rocks 



MOUNTAIN LIMESTONE 



A careful examination of a geological map will show isolated 

 patches of rock. A patch or band of older rock surrounded by newer 

 is called an inlier, and a patch or band of newer rock surrounded by older 

 an outlier. Both of these may be due to denudation of horizontal 

 strata in which case the former are situate in the valleys and the latter 



4 



