Bev. A. Irving — Geology of the Nottingham District. 317 



sandstones, distinctly angular, are to be met witla imbedded in the 

 hard sand rock. The Castle rock, which overlooks the Trent, is of 

 this sub-formation, and most of Notting^ham is built upon it. Thei 

 ancient cave- dwellings, which gave the name to the town, are ex- 

 cavated in it. The Castle rock is traversed by a series of ^ master- 

 joints,' running in a north-westerly direction ; and joints parallel to 

 these are to be observed at intervals all along the southern face of tlie 

 roclc The valleys formed by the erosion of this rock, and opening 

 upon the Trent Valley, appear to have bad their direction determined 

 by these joints, which, as lines of weakness, must have facilitated 

 denudation. 



The UjDper Eed and Mottled Sandstone, wMeh overlies the Pebble 

 beds in some parts of tbe Triassic area, but is usually considered to 

 be wholly wanting in this district, seems nevertheless to be repre- 

 sented by some fragmentary patches. From a description of one 

 of these, so high an authority as Professor Hull has been led to 

 acquiesce in this view of the author's ; but most of it was denuded 

 away in tbe interval between Bunter and Keuperian times. 



The present Bunter country includes the old forest-lands of Sher- 

 wood. It offers great advantages for water-supply, its porosity and. 

 underlier of marl allowing it to act as a huge resei"voir, 



(4). The Keuper. — The Lower Keuper strata or " Waterston-es," 

 consisting of alternating beds of sandstones and marls, are seen, in 

 the few sections where the junction is exposed, resting upon tbe 

 eroded or denuded surface of the Bunter. Cl-ose to Nottingham this 

 has been observed, (1) in Eed Lane, (2) in a culvert now covered 

 over on tbe east side of the town (by Mr, E. Wilson, F.G.S.)- At 

 both these places the junction is marked by a bed of highly calcareous 

 breccia, and there is uneonformability between the two formations. 

 The junction is also exposed in the hill-side east of Sneinton, where 

 there is a marly breccia ; and a still more interesting example of it 

 was to be seen a short time ago in a culvert at the foot of Blue-bell 

 Hill, close to Nottingham. Here the junction is marked by a hard 

 red conglomerate (1 foot thick). This is surmounted by 8 feet of 

 Keuper sandstones, interbedded with three well-marked layers of 

 ochreous-yellow limestone, each about 3 inches thick. May not 

 these be homotaxial with part of the Muschelkalk ? Above these 

 the marls and ripple-marked sandstones come in. Some good 

 sections of the Lower Keuper, showing the passage into the Upper 

 Eed Marls, may now be seen in the cuttings and tunnel of the 

 railway in course of construction on the north-east of Nottingham. 

 Footprints of CJieirotherium have been observed at Castle Donning- 

 ton, and recently by the author at Colwick, near Nottingham. Eain- 

 pittings, sun-cracks, and ripple-marks are also frequently met with. 

 The latter are so common on the blocks of mudstone brought from 

 beneath the Mapperley Plains as to form the rule rather than the 

 exception. 



The Upper Keuper strata are much more marly in character than 

 the Lower. The two members of the formation may be seen side by 

 side, where a fault intersects the face of the cliff that overhangs the 



