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On the Cornbrash of the neighbourhood of Cirencester. By 

 James Buckman, F.L.S., F.G.S., Professor of Geology, Royal 

 Agricultural College. 



Read 20th September 1853. 



The Cornbrash as it occurs in the neighbourhood of Cirencester, 

 though for the most part a very thin member of the Oolitic 

 series of rocks, yet presents us with many points for consider- 

 ation of great interest. 



In the counties of Gloucester and Wilts it is always found to 

 rest upon a thick bed of Forest marble clay, a section at Kemble, 

 four miles from Cirencester, being as follows in descending 

 order : — 



1. Cornbrash, an oolitic stone, with rough uneven fracture and ft. in. 



full of shells 8 



2. Blue clay without shells ) Forest 17 



Siliceous limestone ... / marble 6 



4. Bradford clay, very fossiliferous 7 



5. Great Oolite 



The bed No. 1, which it is our object to describe in the fol- 

 lowing remarks, though of so slight thickness, is found to be the 

 substratum of large tracts of land, especially in the neighbour- 

 hood of Cirencester, Fairford, Cricklade, and Malmsbury; in 

 each case presenting great and beneficial peculiarities of soil, 

 not only when compared with that upon its surrounding forest 

 marble, but also in comparison with other oolitic brashes; in- 

 deed, its name " Cornbrash " would appear to have been given 

 to it from the fact that its soil affords a brash or stony soil 

 favourable for corn crops, which is far from usually being the 

 case with those either of the Inferior or Great Oolitic beds ; in- 

 deed our observations of crops upon what the Cotteswold farmer 

 calls " stone brashes " of the district, when compared with the 

 Cornbrash, would lead us to conclude the following as a fair 

 average grown upon an acre in bushels : — 



