CHLORITIC MARL. gj 



great part of the Island the outcrop of the Chlorltic Marl is so 

 narrow that a single line suflSces on the one-inch map to cover it ; 

 but around the Southern Downs and near Gatcombe, where the 

 dip is gentle, the Chloritic Marl runs up the dip-slope of the 

 Chert Beds considerably beyond the foot of the Chalk Downs, 

 ending off along an irregular line marked neither by featm-e nor 

 change of soil. In such cases, the line at the base of the Chalk 

 has been engraved, as the only boundary capable of being traced 

 with any accuracy. 



In Compton Bay, the Chloritic Marl, 13 feet thick, consists 

 of marly sand with much glauconite and numerous pale-brown 

 phosphatic nodules, most of which are the rolled casts of 

 Ammonites (chiefly A. varians), Turrilites Bergeri and bivalves. 

 Some lines of irregular-shaped concretionary masses in it may 

 possibly be imperfectly formed chert. The same subdivision is 

 again well exposed in the road-cutting above Brook {see p. 70), 

 where it is 11^ feet thick, and contains abundant rolled casts of 

 Ammonites varians. The same description will apply also to the 

 section in the chalk-pits on the Brixton and Calbourne road. 



In the UnderclifF the Chloritic Marl is well exposed, some of 

 the best sections being on the top of Gore Clift', and on the cliff 

 above St. Lawrence, in the zig-zag road at Ventnor, at the 

 railway station and 100 yards east of it, and in a pit by the road- 

 side near the Pulpit Rock above Bonchurch. It is about 7 feet 

 thick, and consists in the upper part of marly sand with 

 glauconite and many phosphatised casts of fossils, and in the lower 

 part of laminated sand of a darker tint, with broken shells of 

 Pecten asper, while between the two bands there runs a line of hard 

 white stony lumps. The old coprolite diggings, before alluded 

 to, were in the upper part of the Chloritic Marl and may still be 

 distinguished on the edge of Gore Cliff, on either side of the 

 township boundary. 



In Culver Clifl', the upper limit of the Chloritic Marl is difficult 

 to fix. If it is taken at the base of the lowest bed that can be 

 fairly called chalk, the thickness obtained for the Chloritic Marl 

 is 15 feet, the section being as follows: — 



Ft. In. 



Chalk Marl (see p. 89). 



f Green marly sand with lines of ^rey concre- 



Jtions, with Plocoscyphia, and a few scattered 

 phosphates .- - - 



Do. with phosphatised Ammonites - 

 I Line of large lumps of very hard grey stone 

 Very green sand, with pipe-like markings, 

 (^ and a few phosphates . . - 



Chert Beds (see p. 70). 



Inland the Chloritic Marl being very soft is usually hidden, 

 but sections of it may be seen 100 yards south-east of Garstons, in 

 the roadside by the Convent at Carisbrook, and at Frogland, 



E 56786. V 



