1865.] 



AYHITAKEK ISLE OF WIGHT CHALK. 



403 



Layer of hard yellowish nodules. A line of grey clay above, 

 and two feet higher another less-marked nodular bed. 



Bedded chalk. 

 In the large pit at the south-western end of Brixton Down there 

 is again in the midst of the chalk a thin hard bed, like the Chalk- 

 rock, with a clearly marked layer of green-coated nodules and lumps 

 of octahedral iron-pyrites at its top, the bottom, on the contrary, 

 not being defined. A foot or so above is a line of clay, which seems 

 to show an unconformity (or false bedding ?) in the Chalk *; for 

 southwards it is further from the nodular bed, whilst northwards 

 the latter is not seen, but seems to be cut off, the section there being 

 as in fig. 3 ; at the northern and deepest part of the pit, however, 

 the nodules come on again, and the section is : — 



Chalk with a few nodular flints, the upper part weathering 

 flaggy, the lower part with a rough surface. 



Layer of nodules, &c., hard, the bottom not clear. 



Bedded chalk ; no flints, but lines of soft marl. 



Fig. 3. — Diagram-section of a small part of a Cluilh-pit on Brixton 



Down. 



^^ 





4-U- 



M 



, —Ml! 



M 11 \^r^ — 



ii 



III \\ 



%\i^' 



a. The line of clay above the Chalk-roek (in other parts of the section). 



b. Another line of clay. c. Chalk much split up. 



A little way below this pit the hard bedded Chalk-marl is shown, 

 and then the top part of the Upper Greensand (grey and green sand 

 with stony layers) . 



In the quarry, marked on the Geological Survey Map, just east of 

 Carisbrooke Castle there are some beds of hard nodular chalk : in 

 one of these the nodules are cream-coloured and green-coated, as in 

 the Chalk-rock ; seven or eight feet above is a seam of black shaly 

 clay, and another of grey clay lower down. I saw no flints here. 



The new road-cutting just below, and south of, the large chalk- 

 pit at the western end of Arreton Down is in the Chalk-with-flints ; 

 whilst an old pit still lower, and west of the road, shows challi with 

 a very few flints and weathering to a rough surface, and at the 



* I believe that M. Ilebert has observed unconformity between different divi- 

 sions of the Chalk in France ; and Mr. Webster has described and figured a 

 remarkable case, in the midst of the Chalk-with-flints. at Handfast Point (Sir 

 H. Englefield's ' Isle of Wight,' p. 164, plates 26, 27), which, however, is looked 

 on by many geologists as a fault. I have not seen it myself. 



