318 Rev. A. Irving — Geology of the Nottingham District. 



Midland Eailway and faces Colwick Hall. The tipper series is 

 marked here, as elsewhere, by the comparative absence of sandstones 

 and the abundance of veins of satin-spar or "fibrous gypsum." Here 

 and elsewhere the author has noticed a general tendency of the direc- 

 tion of the long prismatic crystals to-wards the vertical; a phenomenon 

 as yet unexplained so far as he is aware. Gypsum, of a more amor- 

 phous character ("alabaster") is largely quarried at Chellaston and 

 Aston (where beds occur 9 feet in thickness), at Thrumpton, and at 

 Newark. At the last-named place the beds are about a foot in thick- 

 ness, though one bed attains a thickness of three feet, with numerous 

 thin veins ramifying in all directions, quite irrespectively of the planes 

 of bedding of the marl. Eounded and lenticular masses of gypsum 

 (some pure white, others of a delicate flesh-colour) are found here 

 also, and have so contorted the strata above them as to give proof of 

 their consolidation subsequently to the deposit of the marls. Pseudo- 

 morphs of rock-salt have been found in the uppermost beds of the 

 marls at Newark, Colwick, Blue-bell Hill, and Carlton, in addition 

 to the places mentioned by the Government Geological Surveyors. 

 The author has in his possession a slab (picked up at Newark by one 

 of his pupils) on which the pseudomorphs are interspersed with fish- 

 scales — precursors, as it were, of the Rhastic bone-bed. The total 

 thickness of the Keuper is little, if any, more than 200 feet. 



(5). The BJicetic Beds. The black paper-shales were discovered by 

 Mr. Etheridge a short time ago, at Elton, near Nottingham,, on the 

 Great Northern Branch line ;. and the author has found there also a 

 portion of the ' bone-bed.' 



A section of Eheetic beds was found by the author last spring 

 outside Newark, where are seen : 



1. Black ' paper - shales ' abounding along, a certain feet. 



horizon in Avicula contorta and Pullastra arenicola 10 



2. Grey and greenish marls ... 15 



—25 

 The uppermost zone,, or ' White Lias,' is not seen in situ, but what 

 appear to be fragments of it are foimd in the soil above, and, in 

 one place, among a mass of disturbed materials, composed of black 

 shales, much broken up and mingled with pebbles apparently from 

 the Bunter. This mass is probably in one sense a ' boulder-clay.' 



Another section of the Eheetic has quite recently been brought to 

 light at ' Spinney Hill ' near Leicester, and noted by Mr. J. J. H. 

 Teall, B.A., F.G.S. 



(6). The Lias. — This formation plays but a subordinate part in 

 the geology of the district, until we get into Leicestershire and the 

 Vale of Belvoir, It caps the hills about Gotham and Thrumpton 

 along the south side of the Trent, where no doubt Ehsetic Beds 

 might be discovered by digging into the flank of the hills. Belvoir 

 Castle surmounts an escarpment of Marlstone of the Middle Lias, 

 which abounds there, as in the Banbury district, with Bhjnchonella 

 tetrahedra and Terehratula punctata. 



(7). Drift and Alluvium. — A great part of the former appears 

 to have been carried down into the valley of the Trent, where 



