364 STKATIGEAPHICAL GEOLOGY 



In the Worcester, Warwick, and Leicester areas a bed of grey 

 sandstone, about 20 to 30 feet thick, occurs near the top of the 

 series and is known as the Shrewley sandstone, from Shrewley 

 between Birmingham and Warwick, where it is well exposed. It 

 has yielded remains of fish (Palceoniscus superstes), with Estherict 

 minuta and some casts of bivalve Mollusca, which, according to 

 Mr. E. F. Newton, resemble Goniomya, Pholadomya, and Thracia. 



2. North- Eastern Area 



Basement Beds. Near Nottingham these are repre- 

 sented by an irregular deposit of white sand, which rests on an 

 eroded surface of the Bunter Pebble Beds and varies from a few 

 inches to many feet in thickness. Mr. J. Shipman has described 

 certain pebbly sandstones more than 100 feet thick, which he 

 regards as representing this deposit. 8 



The Waterstones which succeed generally have a pebbly or 

 conglomeratic bed at the base, and this rests sometimes on the 

 white sand deposit, and sometimes directly on the Bunter, but 

 always on an eroded surface, so that it seems to be unconformable 

 to the beds below. The pebbles are chiefly quartz and quartzite, 

 but Mr. Shipman has detected fragments of trap, slate, chert, and 

 magnesian limestone. The waterstones themselves consist of soft 

 brown sandstones interstratified with red marls, which cause 

 plentiful springs by throwing out the water collected in the sand- 

 stones. Ripple-marks and sun-cracks are frequent in these beds. 



The Keuper Marls. These are considered to begin when 

 the marl bands become thicker and the interbedded sandstones 

 become harder and generally white or bluish-grey. Of such beds 

 there is about 150 feet. Gypsum occurs in the marls, and the 

 higher beds are chiefly marl with sheets and nodules of gypsum. 

 The whole is about 900 feet thick (see Fig. 118). 



In Yorkshire, the Keuper appears to become thinner and not to 

 exceed 700 feet in thickness ; it is still capable of division into an 

 upper red marl group, about 400 feet thick, and a lower series of 

 red and white sandstones from 200 to 300 feet thick, but its 

 lower limit is somewhat uncertain in the northern part of the 

 county. 



3. Cumberland and Irish Sea Area 



Beds of Keuper age overlie the St. Bees' sandstone in the 

 Carlisle basin, and so far resemble the Midland type that they 

 consist of a lower sandstone division and an upper gypsiferous 

 marl group. The former is known as the Kirklinton sandstone 



