THE JURASSIC SYSTEM 393 



aii'l Vnrk. AnctliiT line coast section is exposed in the cliffs of the 

 hire coast between lledcar and Whitby. 



Outlying tracts of Lias occur in Staffordshire, at Needwood 

 Forest and north of Abbots Bromley ; in Shropshire, between 

 Wrin and Audlein, and in Cumberland, near Carlisle, proving 

 that the formation originally extended far to the north-west of its 

 main line of outcrop. There is little doubt, indeed, that the 

 Lias was once coextensive with the Trias, but there is no indication 

 that it ever extended very far beyond the limits of the Keuper 

 marla 



In Ireland Liassic rocks crop out in certain places from beneath 

 the Cretaceous rocks of Antrim, and in Scotland remnants of Lias 

 occur above the Trias on the west coast and on the east coast of 

 Sutherland. 



With regard to the eastward subterranean extension of the Lias 

 in England, it is known that its upper beds, as they pass beneath 

 the higher members of the Jurassic System, thin very rapidly. 

 Thus in a Ixn-ing at Burford, in Oxfordshire, the Middle and Upper 

 Lias are together less than 30 feet thick ; the Lower Lias is there 

 about 620 feet thick, and the Rhoetic is 10 or 12 feet ; but between 

 that place and Richmond the Lias has wholly disappeared, allowing 

 rocks of the Middle Jurassic Series to rest directly on rocks which 

 are either of Triassic or of Old Red Sandstone age. It would 

 appear, therefore, that between Richmond and the Malvern Hills 

 the width of ground now occupied by the Lias is less than 100 

 miles. No trace of Lias has been found in any of the deep borings 

 that have been made in the eastern counties. Northward it may 

 underlie part of Cambridgeshire, but it thins out beneath Suffolk, 

 a boring at Culford, near Bury St. Edmunds, having proved 

 Cretaceous Beds to rest directly on the Palaeozoic rocks. 



The chief zonal and provincial features of the British Lias may 

 be indicated under the head of four provincial areas : (1) the 

 south-west province, including Dorset, Somerset, Gloucester, and 

 Glamorgan ; (2) The Midland Counties from Oxfordshire to the 

 Humber ; (3) Yorkshire ; (4) Cumberland, Ireland, and Scotland. 



1. The South- West Province 



An excellent section of the whole Liassic Series is exhibited in 

 the cliffs of the south coast of Dorset, from Lyme Regis on the 

 west to Bridport on the east (see Fig. 130), and this may be regarded 

 as the typical section of the English Lias, though some of the zones 

 in the Lower Lias are not so fully developed as they are in the 

 Midlands. 



