Vol. 57.] UPPER GEEENSAND AND CHLORITIC MARL OF WILTSHIRE. 97 



old Geological Survey map ; and as one of us (J. S.) has practically 

 re-surveyed this line from Maiden Bradley to Mere, we are able to 

 present a corrected version of it, based on the new 1-inch map 

 (P]. III). Our map also shows the upper limit of the Lower Chalk, 

 that line too having been traced by the author resident at Maiden 

 Eradley. 



The southern boundary of the Cretaceous area is a line of fault 

 running by Bourton, Zeals House, Mere, and West Knoyle, bringing 

 the Green sand and Chalk against Coral Rag and Kimeridge Clay. 



Nearly all the field-work on which this paper is based has'been 

 carried out by Mr. Scanes, acting under the guidance of Mr. Jukes- 

 Browne, to whom he sent measurements of each section, accom- 

 panied by samples of every bed measured. Mr. Scanes has also 

 spent much time in collecting carefully and separately from such 

 beds as contained fossils ; and examples of all that were found have 

 been sent to Mr. Jukes-Browne, by whom they have been identified 

 so far as present knowledge permits, but some of the species appear 

 to be new, especially among the gasteropoda. Prom these data the 

 following account of the exposures and the lists of fossils have been 

 drawn up. 



II. General Succession in the District. 



The general structure of the district wq^ well described by a 

 correspondent of Fitton's, who printed the account, with a sketch- 

 section and some comments of his own, in his well-known memoir 

 on the ' Strata between the Chalk & the Oxford Oolite.' ^ It appears 

 that a well had been sunk near the foot of Whitesheet Hill, and 

 that the well-sinker gave the following account of the beds tra- 

 versed : — 



Feet. 



(a) Malm, like the Chalk-Marl of Lewes in Sussex, full of the 



cliaracteristic fossils : sharks' teeth in great abundance 100 



(b) ' White stone,' so-called, but in reality rather grey or 



green, full of ammonites, many of which preserve their 

 iridescent coats 4 



(c) ' Chert,' at the lower part rubbly, and there the water 



rose 30 



134 



His 6 is evidently the Chloritic Marl and c the Chert-Beds. The 

 underlying sands are described as loose, but containing 



' huge concretional masses of stone of similar composition (? the Oowstones of 

 the Devonshire coast).' 



The sands are stated to rest upon clay, and Pitton suggests that this 

 clay must include the Gault. 



To the foregoing account we may add that the easterly dip 

 is greater than that shown in the section given by Pitton ; that 



1 Trans. Geol. Soc. ser. 2, vol. iv (183G) p. 256. 

 Q.J.G.S. No. 225. h 



