ij 2 THE STORY OF THE EARTH. 



In Yorkshire the beds which rest on the Lias 

 are known as P %g€r. They are about 90 feet 

 of yellow sand covered by concretions of Oolitic 

 ironstone, usually sandy. Like the Northampton 

 Sands, they are capped by current-bedded sands 

 and shales among which are beds of impure coal. 

 The fossils of those estuarine sands include ferns, 

 a large Equisetum often found erect among the 

 blown -and, and the Cycad Zamia. They indi- 

 cate an bid land surface. The beds which rest 

 upon these sands show a similar want of conti- 

 nuity where they are exposed at the surface oi 

 the country. 



The Inferior Oolite is limited to the west of 

 England. In the Cotswold Hills it is about 250 

 feet thick, mainly limestone. At its base is the 

 pea grit, with concretions about the size of peas. 

 Above it are the Oolite limestones with texture 

 like the hard roe of fish, known to builders as 

 freestone, termed Roe-stone, which alternate with 

 marl. A little sand remains when the limestone 

 is dissolved. The rock thins away to the cast 

 beyond Woodstock. Its fossils include Terebra* 

 tula fimbria^ Pholadomya juiieula, Ostrea Marshii % 

 Cfypem plotii. 



In Northamptonshire the beds are replaced, 

 first, at the base by a thin bedded, shelly lune- 



stone used for roofing, known as Collyweston 

 Slate. It is sometimes 20 tret thick. The great 

 mass of the Inferior Oolite is represented b 

 limestone known as Lincolnshire limestone^ which 



thins away to the north and south. It is 200 

 feet tlu< k at its maximum, and forms an escarp- 

 ment terrace in Northamptonshire and Lincoln- 

 shire. 



In ifC this period of time is repre- 



