GEOLOGY 



TABLE IV. SHOWING THE THICKNESS OF COAL-MEASURES ABOVE THE TOP HARD COAL 



LEFT AFTER PRE-PfiRMIAN (OR PRE-TRIASSIC *) DENUDATION 



ft. ft. 



*Clifton borehole 39 Kirkby 1004 



*Clifton colliery 54 Bestwood 1092 



Kimberley 298 Linby 1262 



Watnall 320 Annesley 1302 



Cinderhill 635 Shireoaks 1308 



Gedling 855 Southcar 1469 



Watnall New 919 



In these tables there are several anomalies. The depths to the Top 

 Hard and to the surface of the Coal-Measures differ greatly in neigh- 

 bouring sinkings without any surface indications of faults. These 

 anomalies, due to unseen or observed dislocations, show that in the interval 

 between Carboniferous and Permian times the Coal-Measures were much 

 broken up. Such faults are occasionally found, as at Cinderhill, to 

 affect in a less degree the overlying strata, in which case the disturbance 

 was repeated, but on a smaller scale. Other faults, like those parallel to 

 the Trent valley, seem to have first occurred in post-Triassic times. 



THE PERMIAN SYSTEM 



The Permian rocks of Nottinghamshire form part of the typical 

 series in England, being continued through Yorkshire into Durham. 

 The fullest development is in the north of this area ; and on going 

 south the divisions one by one die out till the last of them disappears 

 near Wollaton. Everywhere it is a most peculiar formation. Litho- 

 logically it is characterized by the occurrence of a magnesian limestone 

 or dolomite, and by the red and mottled colour of its clays. Palas- 

 ontologically it contains the last relics of the Palasozoic genera, such 

 as Productus, associated with forerunners of Mesozoic types, such as 

 Schizodus. Various rocks have been called Permian in other parts of 

 England, including some, as the Rotherham Red Rock, now known 

 to belong to the Coal-Measures, but only some in Lancashire and 

 Cheshire contain any of the characteristic fossils, and there, as a whole, 

 they are of a different lithological character. 



The unconformity of the Permian to the Coal-Measures is already 

 shown by its resting upon different parts of them in different sinkings 

 and by its being unaffected in whole or in part by many of the faults 

 in that series. The actual junction, demonstrating on a small scale all 

 these features, may be seen in the Great Northern (Erewash Valley 

 Branch) Railway between Hempshill and Kimberley, where it has been 

 described by Mr. Wilson. 1 The unconformity in this district was first 

 recognized in the original description of the series given by Professor 

 Sedgwick. 2 



THE BASEMENT BEDS. The natural basement conglomerate along 



1 <%uart. Journ. Geol. Soc. vol. xxxii. 

 * Trans. Geol. Soc. ser. 2, vol. iii. 



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