GEOLOGY 



Newark and the discovery of a mass of the same mineral 9 feet thick 

 in the Permian Marls at Southcar boring, where no doubt it has been 

 protected from infiltration. The gypsum beds occur principally on two 

 horizons, one not far from the base which has been worked at Clarborough 

 and Little Gringley in the north of the county, and one at about 100 

 feet from the top of the marls worked at Newark, Hawton, Shelton 

 Orston, East Bridgford, Barton, Thrumpton, Gotham and Kingston. 

 The gypsum industry is an important one, 76,584 tons having been 

 raised in the county during 1901, out of 200,000 tons raised in the 

 whole of the United Kingdom. The water also from these works, and 

 that which is used for brewing at Newark, has an analysis closely resem- 

 bling that required for the production of Burton ales, viz : 



Grains per gallon 



Calcium sulphate 84-93 



Magnesium sulphate 23-91 



Calcium carbonate 6'00 



Sodium carbonate 4-45 



Calcium nitrate 4-85 



Sodium chloride 5-76 



Alumina, etc 2-02 



131-92 



The Keuper Marls, from the softness of their materials, do not give 

 rise to such marked escarpments as the Sandstones, but only to more local 

 ones where their own sandstones occur, as round Tuxford and at Leverton 

 and Halam Hill near Southwell. On the other hand water falling on 

 them does not readily sink in, and numerous streams are formed which 

 work their way downwards to a hard band, and thus excavate narrow 

 ravines known as dumbles, filled with underwood, e.g. Lambley Dumble. 



The Keuper beds as a whole occupy the eastern half of the county 

 as far south as Nottingham, at which point their outcrop is continued 

 up the sides of the Trent valley in a westerly direction, connecting the 

 bulk of them with those in the Midlands. Of this area of outcrop the 

 part occupied by the Sandstones is by far the narrower, indicating a 

 much less thickness for this portion. In the borings made on the out- 

 crop we only get a partial estimate of the thickness. These give at 

 Clifton 279 feet, at Edwalton 426 feet, at Ruddington 465 feet, from 

 the base to the middle of the Marls ; at Gedling 75 feet, at Thurgarton 

 273 feet, from the base to the commencement of the Marls ; at Tuxford 

 426 feet, at Southcar 714 feet, from the base to the middle of the Marls ; 

 and at Newark 410 feet of Marls and 175 feet of Sandstone, neither 

 series being complete, are found. In the borings that have commenced 

 on the Lias we get the full thickness at the time the Jurassic period 

 commenced, viz. 633 feet of Marls and 115 feet of Sandstones = 748 feet 

 atOwthorpe, and 688 feet of Marls and 205 feet of Sandstones =89 3 feet 

 at South Scarle. These figures in a general way show a thickening 

 to the east while the shore conglomerates have been mostly found to the 

 west. 



29 



