1857.] BUCKMAN — OOLITES. Ill 



Nettlecomb Bottom ; so that it offers too slight a drainage-area to 

 render reservoirs for the water-supply of the place practicable. 

 Passing along our line of section, dwellings only occur where the 

 surface is a few feet above the Fuller's Earth ; and the hill along 

 which runs the old Roman road from Gloucester to Cirencester, and 

 the parallel Cotteswold heights, have the farm-houses and cottages 

 near the junction of the Great Oolite and Fuller's Earth, water being 

 so important an element in domestic use. This bed too is of great 

 importance in an agricultural point of view, as on the hill-slopes 

 meadows with their ponds can be maintained in the " skeins of clay," 

 as the farmer terms the Fuller's Earth band with which the otherwise 

 brashy land is divided ; so that, although the Great Oolite has a 

 thin soil, the Inferior Oolite is not only watered from the Fuller's 

 Earth above it, but is covered up with a more or less deep soil, partly 

 made up of the latter, — facts easily understood from the following 

 section : — 



Fig. 2. — Section of the Fuller's Earth. 



Elkstone. 



1. Inferior Oolite. 2. Fuller's Earth. 3. Great Oolite. 



a. Debris of Fuller's Earth, making meadow-land. 



b. Position of Ponds. c. Position of Houses. 



So regular is the course of the Fuller's Earth bed, except when cut 

 off by faults, that, on ascertaining the depths of wells at different 

 points, a surface-section can be made out almost as accurate as with 

 the theodolite ; and hence our sections for the most part enable us to 

 determine along their whole lines the depths to water-bearing beds. 



The fossil contents of this bed in the Cotteswold district offers but 

 a comparatively small list, but this is made up by the enormous 

 masses in which most of the species occur ; the following are among 

 the common examples : — 



Ostrea acuminata, M, C. Pecten vagans, M. C. 



Avicula echinata, M. C. Pholadomya truncata, Buckman. 



Terebratula globata, M. C* 



These fossils are usually in such abundance in the upper part of 

 the stratum as merely to be cemented by a marly paste, and the 

 rock, acted upon by the frost, is broken up into a heap of shells. 



5. Great Oolite, with Stonesfield Slate (4.). 



Thi3 is with us a widely-extended rock, and more especially in the 

 South Cotteswolds, commencing a few miles to the north of Ciren- 

 cester, and continuing, with but few interruptions, beyond Bath. 

 Like the Inferior Oolite, it is variable in thickness, and made up of 



* The same as the Inferior Oolite species, but more regular in form, and usu- 

 ally a more delicate-looking shell. 



