220 



exposed in qtiarries at the base of the Kimmeridge clay; 

 they consist of coarse oolitic Freestone, yielding large blocks of 

 building stone, which has been extensively used at Oxford for 

 buildings later than the fifteenth century. This Freestone is 

 12 feet thick, which gives a total of 25 feet for the Coral Eag in 

 this locality." * 



The coralline Oolite is well develox^ed and admirably exposed 

 near Mai ton, Yorkshire, where large quarries of compact thick- 

 bedded freestones are worked, near the town, and yield a rich 

 harvest of organic remains. A beautiful fine-gvained building 

 stone, containing much siliceous matter, is extensively quarried 

 near Hildenley, for church decoration, from which Sir C. 

 Strickland, Bart., whose property it is, has collected a very 

 fine series of fossils. Al Hackness, Ayton, and Seamer, near 

 Scarborough, there are many exposui-es, from whence the 

 madreporic beds of this formation are extensively raised for 

 road material ; they consist of old coral reefs, in beds of from 

 10 to 15 feet in thickness, composed of layers of ciystallized 

 coral rock from 18 to 24 inches in thickness, largely consisting 

 of Thamnasiroea conrAnno, Goldf., and other Anthozoa; each 

 layer being separated from the others by rubbly clay and mud. 

 The largest quany is near Ayton, another is near Seamer, and 

 others are in the neighbourhood of Wykeham and Brompton. 

 The Ayton quarry, which may be considered as the type, 

 contains large nodulated masses of madreporic Limestone, the 

 beds composing it having an u-regular undulating surface. 

 The corals appear to have grown in areas of depression in the 

 coralline sea, for the rock consists of large masses of a very- 

 hard and highly crystalline madreporic Limestone, forming 

 nodulated eminences and concave curves in beds of from 12 

 to 18 inches in thickness, a stratum of yellowish clay filling up 

 the hollows, and forming a horizontal line in the stratification 

 of the bed. A stratum of nodulated crystalline Limestone is 

 covered by a layer of clay, and thus the rock is made up just 



* Memoirs of the Geol. Surv. The Geology of parts of Oxfordshire and 

 Berkshire, (Sheet 13,) by Edward Hull, B.A., and William Whitakee, B.A. : 

 1861. 



