136 NEOZOIC TIME. [CHAP. IX. 



muddy material derived from the waste of the surround- 

 ing land. The shaly layers, which are familiar to us under 

 the name of Lias, are evidently such as were formed in the 

 more central and deeper parts of the sea, and there are 

 only a few localities where littoral beds of this age have 

 been preserved ; but of these it is desirable to give some 

 special account. 



Shore-beds of Lower Liassic age are known in four dis- 

 tricts, viz., the Men dip district, Glamorganshire, the Inner 

 Hebrides, and eastern Sutherland. In the Mendip district, 

 near Shepton-Mallet, the ordinary clays and thin lime- 

 stones pass into massive white limestones, associated with 

 conglomerates composed of Carboniferous Limestone and 

 chert. Again, on the northern flank of the hills near 

 Chewton-Mendip, and Harptree, there is a compact cherty 

 deposit, containing Lower Lias fossils, and resting indiffe- 

 rently on Old Red Sandstone, Carboniferous Limestone, and 

 Dolomitic Conglomerate. 1 



Similar deposits occur in Glamorganshire, near Bridgend, 

 Sutton, Brocastle, and Cowbridge, the basal beds being 

 hard, cherty, conglomeratic limestones, and passing up 

 into massive limestones full of fossils. The Sutton stone 

 is a soft white limestone, and in it corals are particularly 

 abundant. 



In the west of Scotland the lower part of the Lias re- 

 sembles that of South Wales, consisting of hard limestones 

 alternating with calcareous and conglomeratic sandstones. 

 Above these are shelly limestones and shales. On the east 

 coast these beds are represented by estuarine deposits. 

 At the base are coarse sandstones and conglomerates, with 

 pebbles derived from the Lias, and these pass up into a 

 series of sandstones and shales, with thin layers of clay 

 and coal, the whole attaining a thickness of between 400 

 and 500 feet. 



1 Woodward, " Geology of England," second edition, p. 265. 



