Ml*. Lonsdale on the Oolitic District of Bath. 



255 



scribes a line nearly parallel with the heights on the right bank of the Avon 

 to Bradford ; and from that town it may be traced by Upper Westwood to 

 Iford Mill and Farleigh Hungerford, where it dips beneath the forest marble. 



Bradford Clay. 



If it were not for the inconvenience which arises from the change of 

 nameSj it would be desirable to consider the Bradford clay as a portion of the 

 forest marble. In external characters, the argillaceous deposit we are now 

 describing, cannot be distinguished from the beds of clay which are inter- 

 stratified with the grits and shelly limestone of that formation. In both 

 instances the clays contain thin layers of limestone and laminae of grit, which 

 are identical in composition ; and Apiocriniits rotundus, tJie fossil to which 

 the Bradford clay has been indebted for its celebrity, is likewise found in 

 the forest marble. 



Considered however by itself, this deposit consists of a pale grey clay con- 

 taining a small proportion of carbonate of lime, and inclosing thin slabs of a 

 tough, brownish limestone, and laminae of calcareous sandstone or grit. 



The greatest thickness of the Bradford clay appears to be in the neigh- 

 bourhood of Farleigh, where its dimensions are said to be from 40 to 60 feet. 

 It is however frequently wanting. 



The Bradford clay appears forming a thin bed in the neighbourhood of 

 Yatton Keynell and Giddy Hall; but between the latter point and Berfield, 

 near Bradford, it is wanting, the forest marble being visible resting on the 

 great oolite at Pickwick and Wormwood. At Berfield the clay re-appears, 

 constituting a thick stratum, which may be traced from that village by Brad- 

 ford and Upper Westwood to Farleigh. It likewise occurs underlying the 

 forest marble in the ridge to the north of the road from Farleigh to Charter 

 House Hinton ; but through the southern part of the district it is difficult to 

 separate the Bradford clay, if it exists, from the fuller's earth. 



Forest Marble. 

 The strata which are interposed between the great oolite and the cornbrash, 

 when exhibited in their simplest manner, admit of the following arrangement. 



Thickness. 



1. Clay, with occasional laminae of grit ... 15feet. Kington St. Michael's, Norton, &c. 



2. Sand and grit 40 Ibid. Ibid. Frome, &c. 



3. Clay, with thin slabs of stone and la- "1 f Wormwood, Pipe House Hill near 



mina; of grit / ^^ \ Midford. 



4. Shelly limestone or coarse oolite 25 Wormwood, Frome, &c. 



5. Sand or sandy clay and grit 10 Frome, Norton, Baggeridge, &c. &c. 



6. Bradford clay. 



