Vol. 60.] THE KEUPER AND RH^TIC IN GLOUCESTERSHIRE, ETC. 355 



tracts of country to characterize definite horizons ; but the Estlieria- 

 and Pecten-Beds are fairly persistent ; and it is best in correlating 

 the sections to find these horizons first, and with their aid it will 

 be seen that down to Bed 15 the sections admit of satisfactory 

 correlation. In some sections the Bone-Bed does not occur at all, 

 possibly because the surface of the Keuper Marls, or the rock 

 composing the land-surface at the time of its formation, was not 

 sufficiently submerged. 



Down to Bed 15, then, the various sections can be correlated 

 almost bed for bed, and the contemporaneity of deposits which 

 admit of such exact correlation seems most probable. But below 

 Bed 15 we have in one locality no Rhaetic deposit, in another as 

 much as between 7 and 8 feet. 



The writings of our foremost geologists on questions of historical 

 geology show that the Keuper Epoch closed with a scene of arid 

 wastes and an inland sea reduced to slowly- shrinking lakes ; lakes 

 with surrounding land which, I think, was once formed under the 

 waters of the more extensive Keuper sea. Then, as Mr. A. J. 

 Jukes-Browne has written, 



■ the epoch of the Avicula-contorta zone marks the time when the depression had 

 proceeded so far as to submerge the lowest tract of land which lay between the 

 great salt-lakes and the widespreading southern ocean.' 1 



Xow, may not the same forces which caused the depression in the 

 south-east have affected the Keuper rocks and thrown them into 

 slight anticlinal and synclinal flexures? A few lakes would still 

 remain, but with their outlines somewhat modified by these earth- 

 movements. 



Mr. S. S. Buckman, F.G.S., has indicated the axes of certain 

 anticlines and synclines in the Inferior- Oolite Beds of the Mid- 

 and Xorth Cotteswolds among other regions. Such flexuring caused 

 the Bajocian Denudation, and there is moreover evidence to show 

 that flexuring along practically the same lines of weakness took place 

 about the middle of the Harpoceratan Age or in early Ludwigian 

 times (-post-Lilli, yre-scissi). Also earth-pressures were at work 

 during the hemera concavi. It seems reasonable to suppose that 

 the Liassic rocks might have been similarly affected long before the 

 epoch in which the Inferior-Oolite Beds were laid down : indeed, 

 Mr. Buckman has remarked that the Lias in the Dundry area ' was 

 laid down on a constantly-moving surface.' 2 



Certain of the anticlinal and synclinal axes noticed by Mr. Buck- 

 man in his description of the causes and effects of the Bajocian 

 Denudation may be now mentioned. The most important anticline 

 is along the Moreton Valley, and if the line of elevation be produced 

 in a northerly direction it will be found to coincide with the Pennine 

 axis. A synclinal axis is noticeable at Cleeve Hill; an anticline 

 at Birdlip : and a syncline again between Stroud and Painswick. 



1 * The Building of the British Isles ' 2nd ed. (1892) p. 222. 



2 Proc. Geol. Assoc, voi. svii (1902) p. 153. 



