222 Geological Society : — 



Wrekin itself, whilst the Uriconian beds of other localities, and 

 especially those of Charlton Hill, contained waterworn pebbles, 

 chiefly metamorphic. These pebbles appeared to have been derived 

 from metamorphic rocks of three distinct types. The views put 

 forward were founded on microscopical evidence, of which some 

 details were given in the paper, and were supported by the views of 

 Prof. Bonney, who had furnished notes on the microscopical charac- 

 ters of the rocks. 



3. " Notes on the Relations of the Lincolnshire Carstone." By 

 A. Strahan, Esq., M.A., E.G.S. 



The Lincolnshire Carstone has hitherto been supposed to be 

 correlative with the upper part of the Speeton series, and to be quite 

 unconformably overlain by the Red Chalk (Quart. Journ. Geol. Soc. 

 vol. xxvi. pp. 326-347). But the overlap of the Carstone by the 

 Red Chalk, which seemed to favour this view, is due to the northerly 

 attenuation, which is shared by nearly all the Secondary rocks of 

 Lincolnshire. Moreover, the Carstone rests on different members 

 of the Tealby group, and presents a strong contrast to them in litho- 

 logical character, and in being, except for the derived fauna, entirely 

 unfossiliferous. It is composed of such materials as would result 

 from the " washing " of the Tealby beds. 



In general it is a reddish-brown grit, made up of small quartz- 

 grains, flakes and spherical grains of iron-oxide, with rolled phos- 

 phatic nodules. Towards the south, where it is thick, the nodules 

 are small and sporadic. Northwards, as the Carstone loses in thick- 

 ness, they increase in size and abundance, so as to form a " coprolite- 

 bed," and have yielded specimens of Ammonites speetonensis, A. plic- 

 omphalus, Lucina, &c. When the Carstone finally thins out, the 

 conglomeratic character invades the Red Chalk, similar nodules 

 being then found in this rock. 



The presence of these nodules, with Neocomian species, taken in 

 connexion with the character of the materials of the Carstone, points 

 to considerable erosion of the Tealby beds. On the other hand, 

 there is a passage from the Carstone up into the Red Chalk. It 

 would seem, then, that the Carstone should be regarded as a " base- 

 ment-bed " of the Upper Cretaceous rocks. 



The Lincolnshire Carstone is probably equivalent to the whole of 

 the Hunstanton Neocomian, the impersistent clay of the latter being 

 a very improbable representative of the Tealby Clay. It therefore 

 follows that the whole Speeton series is absent in Norfolk, and also 

 in Bedfordshire. The unconformity at the base of the Carstone 

 becomes greater southwards, and the nodules have been derived 

 from older rocks. Similarly north of Lincolnshire, where the Spee- 

 ton series is overlapped, the nodules in the Red Chalk, marking the 

 horizon of the Carstone, have been derived from oolitic rocks. 



In the South of England it would seem that equivalents of the 

 Speeton series reappear. The Atherfield clay contains an indigenous 

 Upper Speeton fauna, while a pebble-bed near the base of the Folke- 

 stone beds is described by Mr. Meyer as containing derived oolitic 



