96 MESSES. JUKES-BROWNE AND SCANES ON THE [Feb. I9OI, 



8. On the Uppee Geeensand and Chloeitic Mael of Meee and 



Maiden Beadley in Wiltshiee. By A. J. Jde:es-Beowne, Esq., 



B.A., F.G.S., and John Scanes, Esq. (Read December 19th, 



1900.) 



[Plates III-V.] 



Contents. 



Page 



I. Introduction 96 



II. General Succession in the District 97 



III. Exposures of Gault 98 



IV. Exposures of Malmstone and Micaceous Sands 98 



V. Exposures of Cbert-Beds and Chloritic Marl 100 



VI. List of Fossils from the Chert-Beds and Junction-Beds . 114 

 VII. Conclusions 120 



I. Inteodijctton. 



The object of this communication is to give some account of the 

 geology of a little known district on the borders of V^iltshire 

 and Somerset ; a district which includes the parishes of Mere, 

 Stourton, Kilmington, Maiden Bradley, and Horningsham. This 

 area is included in Sheet 19 of the old 1-inch Ordnance Map and 

 in Sheet 297 of the new series of maps. 



It is a high watershed-area, from which streams flow into four 

 different rivers. At Stourton are the sources of the Stour which 

 flows southward ; at Kilmington is a bourn which flows eastward 

 into the Deverill Brook, and is consequently one of the sources of 

 the Eiver Wily ; near Maiden Bradley are springs from which 

 watercourses run northward into the Frome ; while of the waters 

 which issue from the western border of the high ground, some join 

 the Frome and others are tributaries of the Brue. 



The greater part of the area is occupied by sandy beds of. Sel- 

 bornian age, usually known as Upper Greensand ; these form a 

 high plateau, which rises gradually westward and terminates in 

 a bold escarpment, overlooking the lower ground, formed by the 

 outcrop of the Oxford Clay and Lower Oolites, in the valleys of the 

 Brue and the Frome. The summit-ridge of this escarpment rises 

 in several places to over 800 feet, the highest point being Alfred's 

 Tower, marked as 854 feet. Eastward the Greensand plateau slopes 

 below the Chalk, which forms a second bold, but more broken, 

 escarpment rising to nearly the same height, and in one advanced 

 knoll or promontory to 945 feet. 



This district was mapped by the oflicers of the Geological Survey 

 in 1845, and the mapping has not been revised since ; but, from a 

 revision of the adjoining tract to the north in 1889, it became known 

 that the Gault was continuous beneath the Upper Greensand, and 

 consequently this clay was shown on the recent Index Map of the 

 Geological Survey. 



The base of the Chalk is not very accurately indicated on the 



