120 GEOLOGICAL DEPOSITS OF GREAT BRITAIN. 



we find these deposits occurring in the Isle of Wight, and 

 the adjacent counties of Hampshire and Dorsetshire ; they 

 appear in the metropolis and its vicinity, the valley of the 

 Thames, comprising the county of Middlesex, with por- 

 tions of Essex, Kent, Surrey, and Sussex ; they re-appear 

 in the crag of Norfolk and Suffolk, and are traced in York- 

 shire, and in part of Scotland. The chalk succeeds, occupy- 

 ing portions of Sussex, Surrey, Kent, Hants, Dorset, Wilts ; 

 and dipping under the valley of the Thames, occurs north of 

 London, in the counties of Hertford, Bedford, Buckingham, 

 Oxford, Norfolk, Lincoln, and York. The local deposits of 

 the weald fill up the interval between the chalk hills of 

 Surrey and Sussex, known as the North and South Downs, 

 and appear, to a slight extent, in Wiltshire. The oolite 

 group follows, commencing at the Isle of Portland, it pur- 

 sues a winding course through the centre of England, 

 from the south-eastern to the north-western shores ; pro- 

 ceeding through the counties of Dorset, Wilts, Berks, 

 Gloucester, Oxford, Rutland, Northampton, Lincoln, and 

 York, where it terminates in the vicinity of Scarborough. 

 The lias succeeds in order, and commencing at Lyme Regis, 

 follows a similar and uneven course, in the same direction, 

 through the counties of Dorset, Wilts, Berks, Somerset, 

 Gloucester, Warwick, Leicester, Nottingham, and Lincoln, 

 into Yorkshire, where it is traced to the sea-coast, and 

 the cliffs of Redcar, near the mouth of the Tees. The 

 new red sandstone commences in the vicinity of Exeter, 

 and pursues a similar direction through the midland dis- 

 tricts ; traverses the counties of Devon, Somerset, War- 

 wick, Stafford, Nottingham, Lancashire, Cheshire, and Cum- 

 berland, where it gives place to slaty rocks, of older date. 

 The magnesian limestone, an associate deposit, is developed 

 from the Trent to the Tyne, in the counties of Nottingham, 

 Shropshire, York, Westmoreland, and Durham. The coal 

 formation follows no regular course, but is distributed in 

 local areas, called basins. The principal, commencing with 

 the south, are those of Somersetshire, Gloucestershire, 

 North and South Wales, Worcestershire, Staffordshire, 

 Warwickshire, Leicestershire, Derbyshire, Nottinghamshire, 

 Lancashire, Yorkshire, Cumberland, Durham, and Nor- 

 thumberland; and in Scotland, those of the Forth and 



