FOREST MARBLE. 305 



The following divisions of the beds in Somersetshire and Wilt- 

 shire were made by Lonsdale : ' — 



Feet. 



'6. Clay with occasional laminae of grit 15 



5. Sand and Grit = Hinton Sand and Sandstone of W. 



Smith, at Charterhouse Hinton, near Bath - 40 



Clay, with thin slabs of stone, and lamince of grit 10 



3. Shelly limestone or coarse oolite 25 



2. Sand or sandy clay and grit 10 



^i. Bradford clay. 



Forest 



Marble. 



The Hinton Sand contains large concretionary masses of hard 

 sandstone, sometimes in the form known as ' pot-lids.' These beds 

 occur also at Norris Hill, north-west of Westbury. 



INIany fossils have been obtained from the neighbourhood of 

 Atford, between Bath and Melksham, and in the railway-cutting 

 west of Laycock. Northwards the beds extend by Corsham and 

 Castle Combe, to Badminton, Tetbury, ]\Ialmesbury,and Cirencester. 

 Here and there beds of sand with pot-lids occur. 



In Oxfordshire the thickness averages twenty-five feet. At 

 Blenheim Park the thickness is fourteen or fifteen feet. Prof. Hull 

 has observed that owing to the rapid inclosure of Wychwood 

 Forest, many quarries have been opened, showing the lower beds 

 (resting on the Great Oolite) to consist of false-bedded shelly 

 oolite, splitting into slabs and flags, and composed of enormous 

 quantities of broken oyster-shells ; they are about thirty feet in 

 thickness. The higher beds consist of bluish clays and marls, with 

 thin flagstones and roofing-slates, from twenty to thirty feet in 

 thickness. Towards Witney the Forest Mable becomes very thin ; 

 but the beds have been traced to near Bucknell, north-west of 

 Bicester, and west of Pattishall, north-west of Towcester.^ As 

 remarked by Prof. Judd, in Oxfordshire the limestones thin out and 

 disappear altogether, and the clays with occasional shelly bands 

 become so thin that the beds cannot be separated from the Great 

 Oolite. In North Northamptonshire and Lincolnshire the beds of 

 clay again thicken, but they do not include any of the characteristic 

 shelly limestones : hence they have been grouped as the Great 

 Oolite Clay.* The Alwalton Marble near Peterborough may 

 however be a representative of the Forest IMarble. (See p. 316.) 



Economic products, etc. 



Some of the beds furnish coarse roofing-slates and flagstones, as at Poulton, 

 west of Fairford, Cirencester, and Chavenage, near Tetbury. 



Near Milborne Port the beds are worked at Bowden, and known as Bowden 

 Marble ; they are also quarried at North Cheriton and Bratton, near Wincanton, 

 Frome (Frome stone), and many other places. 



1 T. G. S. (2), iii. 255. 



2 Memoirs of W. Smith, by John Phillips, p. 59 ; Q. J. xiv. 87. 



^ Geol. Woodstock (Geol. Survey), p. 22 ; and A. H. Green, Geol. Banbury, 

 p. 26. 



* Geology of Rutland, etc., p. 9. 



