Lias. 571 



laid down for cereals, forms a considerable proportion 

 of our meadow land. It is blue when unweathered,, 

 and includes many beds of limestone, and bands of 

 fossil shells are scattered throughout the clay itself. 

 From its exceeding stiffness and persistent retention of 

 moisture, it is especially adapted for grass land, for it 

 is not easy to plough, and thus a large proportion of it 

 in the centre of England is devoted to pastures, often 

 intersected by numerous footpaths of ancient date, 

 that lead by the pleasant hedge-rows to wooded villages 

 and old timbered farmsteads. When we pass into the 

 Middle Lias, which forms an escarpment overlooking 

 the Lower Lias clay, we find a very fertile soil ; for 

 the Marlstone, as it is called, is much lighter in cha- 

 racter than the more clayey Lower Lias, being formed 

 of a mixture of clay and sand with a considerable pro- 

 portion of lime, derived from the Marlstone Lime-rock 

 itself, and from the intermixture of fossils that often 

 pervade the other strata. The course of the low flat- 

 topped Marlstone hills, well seen in Gloucestershire, and 

 on Edgehill, and all round Banbury, striking along the 

 country and overlooking the Lower Lias clay, is thus 

 usually marked by a strip of peculiarly fertile soil, 

 often dotted with villages and towns with antique 

 churches and handsome towers, built of the brown lime- 

 stone of the formation. 



Ascending the geological scale into the next group, 

 we find the Oolitic rocks formed, for the most part, of 

 beds of limestone, with here and there interstratified 

 clays, some of which, like the Oxford and Kimeridge 

 Clays, are of great thickness, and spread over large 

 tracts of country. The flat tops of these limestone 

 Downs, when they rise to considerable height, as they 

 do on the Cotswold Hills, were, until a comparatively 



