66 



THE GEOLOGIST. 



Subdivisions of British Bocks. — We find space for the following 

 list of the subdivisions of British rocks, as recognized by the Geological 

 Survey, believing it will prove useful to many of our readers. 



Blown sand. 

 Alluvium. 

 Peat. 



} 



Raised beaches. 

 Cave-deposits. 

 Valley, or low-level gravel. 

 Brick-earth. 

 High-level gravel. 

 Glacial drift. 

 Till and boulder clay. 

 Cave-deposits. 



Mammaliferous (Norwich) crag. 

 Red crag. 

 Coralline crag. 

 Leaf bed of Mnll. 

 Lignite of Antrim. 

 Bovey beds. 



Hempstead beds (Isle of 



Wight). 

 Bembridge beds. 

 Osborne beds. 

 Hcaden beds. 

 Upper Bagshot sands. 

 Barton clay. 



Bracklesham sands and 

 clays. 



Lower Bagshot sands and 



clays. 

 London clay. 

 Bognor beds. 



Yi oolwich and Reading beds (plas- 

 tic clav, with sand, pebble-beds, 

 etc.). 



Thanet sands. 



Upper chalk. 

 Lower chalk. 

 Chalk marl. 

 Chloritie marl. 

 Upper grccusand. 

 Gault. 



Folkestone beds. 

 Samlgate beds. 

 Hythc beds, or Kentish 



rng. 

 AthiThYld clay. 

 Weald clay. 



Upper Tunbridge Wells 

 sand. 



Grinstead clay. 

 Lower Tunbridge Wells 



sand. 

 Wadhuist clay. 

 Ashdown sands. 

 Ashburnham beds. 



O r- £ 

 Pm j» <ts 



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f-3 



Lower 

 -eensand. 





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bC 



Lower 



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i d d a 



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J CM £ 



C cS 



J s§ 



1 



Upper Purbeck beds. 

 Middle Purbeck beds. 

 Lower Purbeck beds. 

 Portland stone. 

 Portland sands. 

 Kimmeridge clay. 

 Upper Calcareous grit. 

 Coral rag. 



Lower Calcareous grit. 



Oxford clay and 

 Kelloways rock. 



Cornbrash. 

 Forest marble. 

 Bradford clay. 

 Great, or Bath Oolite. 

 Stonesfield slate. 

 Collyw^eston slate. 

 Northampton sands. 

 Upper Puller's earth. 

 Fuller's earth-rock. 

 Lower Fuller's earth. 

 Inferior Oolite. 

 Lias junction -sands. "] 

 Upper Lias clay, or shale. [ 

 Marlstone. }■ .2 



Lower Lias clay, shale, | ^ 



and limestone. J 

 Westbury beds (or whitel v 



limestone). ^Koessen 

 Bone-bed. J 

 Red marl and 1 

 Upper Keuper sandstone. I 

 Lower Keuper sandstone, f* 

 Marl (waterstoues). J 

 Muschelkalk, absent m~\ 



Britain. 

 St. Cassian beds. 

 Dolomitic conglomerate 



(Somerset and Glou- 

 cestershire). 

 Upper red and 



sandstone. 

 Pebble beds. 

 Lower red and 



sandstone. 

 Upper red marl. 

 Upper magnesian 



stone. 

 Lower red marl. 

 Lower magnesian lime 



stone. 

 Red marl, sandstone. 

 Breccia and 

 Conglomerate, 



beds. 



I 

 I 



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mottled^) 



mottled | 

 J 



lime-1 



Roth- 

 liegeude. 



