122 NEOZOIC TIME. [CHAP. VIII. 



waters of a lake. Ripple-marks, sun-cracks, rain-prints, 

 worm-markings, and the footprints of reptiles are common 

 on their surfaces. 



The red and mottled marls are such as would be formed 

 in the deeper parts of the lake, and they sometimes include 

 beds of sandstone, which contain remains of plants, fish, and 

 small Crustacea (Estheria). The thick beds of rock-salt 

 and gypsum which occur in the marls attest the saline 

 nature of the lacustrine waters. 



The Keuper deposits, like those of the Bunter, are 

 thickest in Cheshire, where they are believed to be over 

 3,000 feet thick. Thence they seem to thin in every direc- 

 tion, but most rapidly to the south and south-east. In 

 Worcestershire the Keuper is only about 900 feet thick, in 

 Gloucester and North Somerset it is much less, and is in 

 some places only represented by shore-beds consisting of 

 sandstone and conglomerate, the pebbles and grains of 

 which are held together by a dolomitic cement, whence it 

 is known as the Dolomitic conglomerate. Elsewhere there 

 are sandstones and marls from 200 to 400 feet thick, the 

 latter containing bands of red and grey limestone, the 

 material of which has clearly been derived from the Car- 

 boniferous Limestone. In West Somerset and Devon the 

 marls and sandstones again thicken to nearly 1,500 feet. 



If we proceed south-eastward from Cheshire, we find the 

 Keuper beds diminished to less than 1,000 feet in South 

 Staffordshire, and to about 700 feet in Warwickshire ; 

 while borings near Northampton disclose the very eastern 

 limits of the formation, its thickness there varying from 

 24 to 82 feet. The Gayton boring is especially interesting, 

 for beneath 60 feet of red Keuper marl and sandstone 

 12 j feet of breccia was found, consisting of large blocks of 

 carboniferous limestone and sandstone embedded in a 

 sandy matrix. Under it was 9J feet of marl and shale, 

 which rested on an eroded surface of a limestone belonging 



