﻿</. Sliipman — Bunter CongJomeraie. 497 



n. — Conglomerate at the Base of the Lower Keuper. 

 By J. Shipman, Esa. 



RECENT excavations for buildings on the east side of Notting- 

 ham have afforded opportunities for observing the true character 

 and development of the conglomerate at the base of the Lower 

 Keuper, which did not exist when this district was visited by the 

 Government Geological Survey. The fact that no fair equivalent of 

 the Muschelkalk of Germany has been met with in England lends 

 an interest to the beds at the junction of the Lower Keuper and the 

 Upper Bunter which they would probably not otherwise possess. 

 Thus the Geological Survey paid special attention to the scanty 

 exposures of this junction that happened to exist twenty years ago 

 in this part. The best section to be seen at that time, near Notting- 

 ham, was in a lane leading from the Mansfield turnpike road, a mile 

 north of the town, to the Mapperley Hills, and is thus described by 

 Mr. Aveline in his memoir on the Nottingham district (Sheet 71, 

 N.E.) : — '•' Near the bottom of the lane there are beds of coarse 

 sandstone [Upper Bunter] slightly consolidated, with pebbles of 

 various coloured quartz, quartz-rock, and other sandstones. There 

 is no good bedding visible in this conglomerate, and lying on it 

 there are thin and regularly-bedded fine sandstones of a red colour. 

 This is the bottom of the Lower Keuper beds, and the line between 

 the two formations is well marked, there being an apparent uncon- 

 formity. There is about twelve feet of this red sandstone, and above 

 it three to four feet of soft red loam, then a thin bed of coarse light 

 sandstone, above this a bed of sand and marl, with some small 

 pebbles of quartz, then alternations of dark and light-brown soft 

 sandstone of various thickness, and red marly shale, which pass up 

 into the Upper Keuper red marly shale with thin beds of white 

 sandstone." Between the Bunter conglomerate beds and the " thin 

 and regularly-bedded fine sandstones " there comes a thin bed of 

 conglomei'ate encrusting the slightly eroded surface of the former, 

 which Mr. Aveline does not appear to have noticed, or, if he did, 

 probably took it to form part of the Bunter. The only conglomerate 

 Mr. Aveline appears to have seen was some sixteen or seven- 

 teen feet above the base of the Keuper. This conglomerate, how- 

 ever, although traceable all over the Keuper area east of Nottingham, 

 consists of merely a few quartz-pebbles imbedded in yellow or 

 greenish-white sandstone, never more than eight inches thick, and, 

 unlike the conglomerate at the base, is not calcareous. It was not 

 nntil two or three years ago that, discovering the calcareous nature 

 of what had been always regarded as the top of the Bunter, I was 

 led to examine the junction at other spots. Since then the further 

 opening up of the ground along the line where the Keuper begins 

 to overlap the Bunter has enabled me to collect tolerably complete 

 data as to the development of the conglomerate in this neighbourhood. 

 It may be here mentioned that chemical analysis has shown that the 

 matrix contains a very large proportion of magniesia as well as lime. 

 Generally the conglomerate is found to occupy the slightly angular, 



DECADE II. VOL. IT. — NO. XI. 32 



