78 GEOLOGY OF THE ISLE OF WIGHT. 



where the Chalk is in a comparatively undisturbed state. 

 Shattered flints may be observed in the large Chalk pits south 

 of Newport and on Arreton Down ; also on Ashey Down, where 

 the Chalk is rather hard, as is most frequently the case where 

 it is inclined at a high angle. The distortion o£ the fossils is 

 noticeable in the pit in the Chalk Marl at Yarbrldge, described 

 on p. 88. 



At Sun Corner, near the Needles, as noticed by Mr. Whitaker,* 

 " there is a bed of some thickness, in which the layers of flint are 

 so close together that they form nearly as much of the rock as 

 the chalk itself." This intensely flinty zone occurs towards the 

 base of the flinty chalk. It is not recognisable in Culver ClifB, 

 but on the other hand the flints are very large immediately below 

 the base of the Tertiary Beds at Brading (p. 96). 



In Culver Cliff a marked flintless zone in the Upper Chalk, 

 about 350-400 feet above its base, was first noticed and described 

 by Mr. Whitaker as follows : — " Here, in the midst of the Chalk 

 with layers of flint at every three or four feet, is a space some 

 forty or fifty feet thick, with only one seam of tabular flint, but 

 with four lines of green-coated nodules, like those of the Chalk- 

 rock but perhaps of a deeper colour." The following 



fossils have been obtained from one of the bands of green nodules :-+- 

 a sponge, a coral, Cardiastcr pillula, Lam., Scrpula plexua, Sow. 

 (adhering to one of the nodules), and Rhijnchonella plicatilis, 

 Sow. These nodules were submitted, for examination under the 

 microscope, to Mr. W. Hill, who kindly furnished the following 

 information concerning them. He found them to consist mainly 

 of the fine amorphous material of the chalk, with a somewhat 

 unusual number of large and perfect foraminifera, and with many 

 sponge spicules, the silica of which had been replaced by calcite. 

 The colouring appeared to be sometimes due to a green material, 

 much of which had accumulated in the interior of foraminiferal 

 cells, but the whole of the amorphous material was sometimes tinted 

 green with no apparent change in its constituent particles. There 

 were no isolated grains of glauconite, such as appear in the some- 

 what similar nodules of the Chalk Eock. After treatment of the 

 nodules with hydrochloric acid, the residue was a dull-greenish soft 

 and earthy-looking material, a large part of which occurred as the 

 casts of foraminifera and the canals of sponge spicules. In some 

 of the nodules Mr. Hill noticed ramifying cylindrical perforations, 

 filled with a white material, shai-ply defined from, and shewing in 

 strong relief against the remainder of the nodule. In the larger 

 perforations there was a greater proportion of foraminifera and 

 shell fragments than in the material of the nodule. In the smaller 

 ramifications the infilling material was like that of the nodule, yet 

 always shewed a clearly defined edge. 



Nodules showing somewhat similar peculiarities occm' at several 

 horizons in the Chalk of the ilainland, and have been remarked 

 by Mr. Hill to bs usually accompanied by an exceptional abun- 



* Quart. Journ. Geoh Soc, vol. xxi. p. 401. 1865. 



