72 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 20, 



five well-pronounced subdivisions, the horizontal range of which 

 throughout the Cotteswold Hills, towards the borders of Oxfordshire, 

 I have already described in a Memoir on the district*. Without 

 entering here into details, I will content myself with stating the 

 following conclusions. The Pea-grit has the smallest range ; next 

 the Upper Freestone ; then the Oolite-marl and Lower Freestone ; 

 and the most persistent member is the Eagstone, which, though 

 never surpassing a thickness of 50 feet, stretches eastward into 

 Oxfordshire, and there becomes the sole representative of the Inferior 

 Oolite. 



I find that this easterly attenuation of the Inferior Oolite is 

 noticed by Professor J. Phillips f, and I refer to it especially as 

 illustrating how small is the relationship between vertical depth 

 and horizontal range. In the case of the Oolites we find that those 

 beds in which there is evidence of current-action, and where the 

 fossils are fragmentary and drifted, the horizontal area is small ; of 

 this the Freestone Series is an example ; but where the beds have 

 been tranquilly deposited, and the fossils have been buried where 

 they lived, the range is greater ; and this is a law more or less 

 applicable to all the sedimentary rocks of which I am treating. 



In the Valley of the Evenlode we can trace the Inferior Oolite 

 as far as Stonesfield, and there it has a thickness of about 15 feet ; 

 but farther east, in the Valley of the Cherwell, at Pousham, it has 

 altogether disappeared, and we find the Great Oolite resting im- 

 mediately on the Upper Lias Clay, or only separated by a thin 

 stratum of ferruginous sand, which must be referred to the Great 

 Oolite J. 



The case of the Inferior Oolite entirely disappearing within a 

 distance of 30 miles south-east of the point where it attains a 

 thickness of nearly 300 feet is remarkable, because it cannot be re- 

 garded altogether in the character of a sedimentary deposit. Many 

 of the Freestone-beds have the characters of shelly gravel, drifted by 

 currents, and these are less persistent; others, as the Oolite-marl 

 and Pagstone, are partly of organic and chemical origin. It is re- 

 markable that the fine of maximum attenuation occupies a nearly 

 parallel direction with that of the more mechanically formed rocks, 

 such as the Lias. 



5. Fuller's Earth. — Of the Fuller's Earth it is only necessary to 

 state that it does not extend as far east as Oxfordshire. In the 

 Cotteswold Hills we meet with it for the last time at Sherborne, near 

 Burford§. But the formation is deserving of notice as being the 

 oldest amongst the Lower Secondary Rocks in which the direction of 

 maximum attenuation changes from the south-east to north-east. 

 In Somersetshire it attains a thickness of 120 feet. 



6. Great Oolite. — The Great Oolite of Gloucester, Oxford, and 



* " Geology of the Country around Cheltenham," 1857 ; Mem. Geol. Survey, 

 t ' Manual of Geology,' p. 303. 



{ Sheet 45, S.W., of the Geological Survey Map ; and " Geology of the 

 Country around Woodstock ;" Mem. Geol. Survey, p. 14. 

 § " Geology of the Country around Cheltenham," p. 52. 



