84 MR. R. L. SHERLOCK ON THE RELATIONSHIP OE THE [Feb. 191 I, 



(c) The Area south of the Great Northern Railway 

 (Nottingham & Derby Branch). 



A little to the south of the Great Northern Railway, at Basford, 

 the Permian Marl ceases to be separable, and the passage-bed rests 

 npon the limestone for a short distance. 



The small faulted outlier at Cinderhill is of interest, as a breccia- 

 band seen there in the quarries has been taken as marking an 

 unconformable junction of the Bunter with the Permian Marl. 

 However, further excavations have shown that the breccia does not 

 always lie at the base of the sandy series, but changes its horizon. 



The growth of Nottingham along the Leen Valley and the com- 

 plicated system of faults which exists there render the strati- 

 graphy very difficult to make out south of Basford ; but, from what 

 can be seen at the present time, and from the records of sewer- 

 sections left by Wilson and Shipman, 1 it appears that the passage- 

 bed and Lower Mottled combined thin out southwards. At Bob- 

 bers Mill the Magnesian Limestone passes rapidly into a breccia 

 and ends abruptly, and the Lower Mottled Sandstone overlaps it. 

 At Spring Close (Lenton), and also at Two Mile Houses (Basford), 

 there are good sections of variegated Lower Mottled Sandstone, and 

 that rock can be followed to the mouth of the Leen. Here the 

 Bunter, which strikes north and south, is dropped out of sight by 

 faults, proved in the workings of Clifton Colliery : with the result 

 that, on crossing the Trent Valley alluvium, Keuper Marl is seen at 

 the surface. 



From the mouth of the Leen, patches of Bunter extend westwards 

 across the Coal Measures, which they overstep ; and at the same 

 time the Lower Mottled Sandstone rapidly disappears, so that Pebble 

 Beds come to rest directly upon the Coal Measures about a mile and 

 a half west of the Leen. 



(d) The Area between the Great Northern Railway 

 (Nottingham & Derby Branch) and the Robin 

 Hood's Hills. 



North of the Great Northern Railway the main outcrop of the 

 Permian Marl follows the Leen Valley, and the junction of the 

 Permian with the Bunter is usually hidden by alluvium. The sur- 

 face of the ground is nearly flat, with a gentle eastward inclination, 

 agreeing in direction with the dip of the beds, the result being that 

 the outcrops of the thin strata are relatively wide. The flat is 

 bounded on the east by the escarpment of the Bunter ; and it is 

 interesting to note that the line of feature does not agree with the 

 boundary of the formation — for, owing to their softness, the passage- 

 beds form part of the flat, and it is not until the more massive sand- 

 rock above crops out that an escarpment is produced. This is very 

 well seen in the cutting on the Midland Railway, at the entrance to 

 the tunnel previously described. It is these more resistant beds 



1 G. W. Lamplugh & others, Mem. Geol. Surv. 1908, pp. 27-28 & 32-33. 



