490 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 2, 



to say. There are, however, mdications tending to throw the balance 

 of evidence on the side of the latter supposition, and this view is in 



Fig. 9. — Section of the Warp-Drift, resting on Great Oolite, at 



Compton Hill. 



a. Warp-Drift ; of brown loam, varying in thickness from 1 to 4 feet ; and con- 



taining a few pebbles probably derived from Northern Drift. 



b. Thin-bedded sandy oolite ; forming lower portion of the Great Oolite forma- 



tion. 



accordance with the fact, that the soils vary rapidly in composition 

 and appearance upon every change in the substratum. 



Dr. Voelcker has also arrived at the same conclusion, founded 

 upon analyses of the soils taken from several formations in the neigh- 

 bourhood of Cirencester. Some of the results he has kindly placed 

 at my disposal, and they will be found appended to this paper. 



Estuarine Deposits. — The estuarine strata of the valleys which 

 surround the hilly district on the north and east sides may be di- 

 stinguished from those of the Northern Drift by the predominance of 

 detritus derived from the waste of local oolitic rocks, either broken 

 up and stratified by the action of the estuarine sea itself, or carried 

 down the slopes from the higher grounds by brooks. These accu- 

 mulations occupy only the valleys and plains, but their stratification 

 cannot be referred to the agency of the present streams. 



Fragments of rocks which have been transported from a distance 

 are generally to be found scattered through the estuarine gravels, but 

 their presence will readily be accounted for when it is recollected that 

 the greater portion of the country was overspread by Northern Drift 

 previous to the estuarine period, and from this deposit these far- 

 fetched pebbles have, in all probability, been derived. Indeed, there 

 is reason for concluding that during this *' second stationary" period 

 a considerable portion of pre\iously formed Northern Drift was re- 

 stratified, and may in this sense be considered estuarine. Accumu- 

 lations referable to the estuarine period occur in the Vale of Bourton, 

 at Paxford, and along the valleys of the Evenlode and Stroud, and 

 overspreading the flat districts of the Oxford Clay to the south of 

 Cirencester. In this last-mentioned neighbourhood, along with the 

 oolitic gravel, chalk-flints occur, derived from the waste of the chalk- 

 escarpments to the south and east. Everywhere these gravels con- 

 tain remains of extinct mammalia, and in Stroud Valley they are re- 

 markably numerous * . 



* Some of these remains are in the possession of Mr. Carpenter, of Caincross ; 

 and a tusk of a fossU elephant in the Museum of the Royal Agricultural College, 

 Cirencester, must originally have measured about 14 feet in length. 



