254 



A. J. Jukes-Browne — The Purheck Beds 



Mr. Woodward rejects our view with the remark that, "to be 

 consistent, however, we must continue to regard the old plane of 

 division as the best, and going again to the district with Mr. Strahan 

 no difficulty was found in determining this junction in the quarries 

 near Tisbury and Chilmark." This strikes me as an extraordinary 

 statement, for I cannot see where consistency comes in, and it is 

 quite impossible to determine the same junction at Wockley and at 

 Chilmark. 



In all such cases where difference of opinion can arise, unless the 

 main facts and features of the exposure are fully described, and 

 unless the thickness of each separate bed is given, with a record of 

 such fossils as come to hand, students who cannot visit the locality 

 themselves are unable to form anything like a correct picture of 

 the section. With this object we give in the Figure a diagrammatic 

 representation of that portion of the quarry-face which includes the 

 beds above mentioned. 



ft. in. 



Section at "VVockley. 



Base of confused beds. 

 Brown and dark grey clay. 



Hard whitish limestone with Cyprides. 



White laminated marl. 



Hard flaggy limestone with black flints at top, Gandona, etc., 



welded on to the top of 

 Chalky limestone, full of the shells of Peeten lainellosus. 

 Parting. 



Rubbly chalky limestone, Avith Fecten lamellosiis. 

 Parting. 



Chalk of usual type with fossils, but no flints. 



2. Division of Lower and Middle Purbecks. — The best exposure of 

 this junction is in the quarry at Teffont, and of this section a full 

 account was given by Mr. Andrews and myself, for he had watched 

 it for many years and had obtained many fossils from the different 

 beds therein exposed. We found Cypridea fasciculata (var. of 

 granulosa) abundant in the ' flagstone bed ' and in the shale above 

 that bed, while in the clay below it was less abundant and was 

 associated with C. purbechensis. This clay-bed may therefore be 

 taken as the junction of the two groups, and it would not matter 

 whether it were included in the one or the other. Mr. Woodward, 

 however, includes the flagstone and some of the overlying beds in 

 the Lower Purbeck, putting the plane of division at the base of the 

 calcareous shale or shaly limestone, which is full of a small Modiola. 



