44 MESSES. W. E. ANDEEWS AND A. J. JUKES-BEOWNE [Feb. 1 894, 



5. The Puebeck Beds of the Vale of Waedoee. By the Rev. W. 

 R. Andeews, M.A., F.G.S., and A. J. Jukes-Beowne, Esq., 

 B.A., F.G.S. (Bead December 6th, 1893.) 



Contents. 



Page 



I. Introduction 44 



II. General Structure of the District 46 



III. The Lower Purbeck Group 48 



IV. The Middle Purbeck Group 53 



V. The Upper Purbeck Group 59 



VI. General Conclusions, and Comparison of Dorset and Wiltshire 



Purbecks 63 



VII. List of Fossils 68 



Map 47 



I. LSTTEODTTCTION. 



Although the Purbeck Beds of the Vale of Wardour have been 

 noticed by many observers, and portions of them have been 

 described by many writers from the time of Fitton downwards, no 

 complete description of the whole series has yet been attempted, 

 and a connected account of the Wiltshire Purbecks seems therefore 

 to be a desideratum in geological literature. 



Fitton gave some account of them in his classical memoir 

 ' On the Strata between the Chalk and the Oxford Oolite,' published 

 in 1836, 1 mentioning quarries at Dallard's Farm, Dashlet, Chicks- 

 grove Mill, and Wockley ; but since his time the Wockley quarry 

 has been cut back, so as to expose the beds which were then only 

 visible at Chicksgrove. He made no attempt to establish any 

 succession, and thought the total thickness of the series was not 

 more than 60 feet. 



The Bev. P. B. Brodie, in 1845, published a little book entitled 

 1 A History of the Fossil Insects in the Secondary Rocks of Eng- 

 land,' in which he gave some description of the Purbeck Beds of 

 the Vale of Wardour, and especially of two beds of limestone, one 

 of which he called the ' Isopod Limestone,' because it contained 

 Archceoniscus, and the other the ' Insect Limestone,' from the 

 abundance of insect-remains in it. Unfortunately, his reference 

 to localities was not very explicit, but it is certain that the quarries 

 " not far from the village of Dinton," where he saw these lime- 

 stones, are not now open, and the details he gave were so different 

 from the Dallard's Farm section described by Fitton that they could 

 not possibly represent the same beds. 



In 1850 Edward Forbes read a paper at the meeting of the 

 British Association at Edinburgh on the Purbeck series of Dorset, 2 

 which he proposed to divide into Lower, Middle, and Upper groups, 

 according to the prevalence of certain species of Cyprids. This paper 



1 Trans. Geol. Soc. ser. 2, vol. iv. pp. 103-388*. 



2 Subsequently published in Edinb. New Phil. Journ. vol. xlix. pp. 391-394. 



