48 MESSRS. W. E. ANDREWS AND A. J. JUKES-BROWNE [Feb. 1 894, 



(3) An anticlinal corresponding with the Teffont Valley, and 

 bringing up the Lower Purbeck Beds into the cutting near Teffont 

 Mill, where they are much disturbed and even contorted. 



(4) A synclinal, with probably a fault, between the first and 

 second cuttings on the line west of Dinton Station. 



(0) An anticlinal seen in the first cutting west of Dinton Station. 



The sketch-map on p. 47 is reduced from the six-inch maps on 

 which we recorded our observations, and we have ventured to draw a 

 complete boundary-line between the Lower and Middle Purbeck 

 Beds, although it should be stated that we did not trace this over 

 the ground, but drew it in afterwards from a consideration of the 

 data collected : these are, however, sufficiently numerous to prevent 

 any serious error. 



The complete discordance between the Purbeck Beds and the 

 Lower Cretaceous series, including the Wealden, is clearly shown by 

 the manner in which the base of the latter passes across the anti- 

 clinal of the Chilmark Valley without being affected thereby. 



III. The Lower Purbeck Group. 



There are two localities in the Vale where the junction of the 

 Portland and Purbeck strata can be examined, namely Chilmark 

 and Wockley ; but, although the two quarries are only two miles 

 apart, the beds seen in the one are so different from those seen in 

 the other that it is hardly possible to compare the two sections. 



It will be convenient to begin with the Chilmark section as being, 

 in some respects, the simplest. This is shown in the higher quarry 

 on the eastern side of the Chilmark Valley, and is as follows : — 



Feet. Inches. 

 ' Shaly marl, with lenticular beds of soft limestone, bed- 

 ding wavy 2 



Yellowish tufaceous limestone 8 



Soft, white, chalky limestone about 1 



Stiff grey clay, containing pebbles of whitish limestone 



and many pieces of wood ; base uneven : from 1 foot to 1 8 

 Pm ■{ Tufaceous marly limestone, very soft in places and ir- 



£ regularly bedded : varies from 5 feet to 6 6 



ps Yellowish oolite, with lenticular layers of brown oolitic 



,3 flint at the top 1 3 



Course of clear brown, glassy flint 3 



Hard, compact, tufaceous limestone 4 



^ Soft, dark grey, marly clay : purplish in places 3 



£ Q - I Firm yellowish oolite in thick beds, the upper surface 



§ 5 i rather uneven seen for 16 



Pw J [ White chalk, with flints, in quarry below 24 



In this section there is no decided break or strong line of division 

 between the Portland and Purbeck Beds. The oolite with the 

 curious oolitic flint is very like that which is classed as Portlandian ; 

 but it seems reasonable to regard the tufaceous limestones as belong- 

 ing to Purbeck rather than to Portland time, and as they contain only 

 a few small bivalves resembling Cyrence we have so classed them, 

 taking the dark clay-band as the basement-bed of the Purbeck series. 



The grey clay which rests on the upper tufaceous limestone is a 

 remarkable bed, and appears to be the relic of an actual terrestrial 



