CHALK. 91 



which the only other traces left are masses of fallen chalk in the 

 Undercliff. Some of the rain-wash, however, from the slopes of 

 this vanished chalk-down forms a conspicuous bed on the brow 

 of the cliff (see posiea, p. 237). There is a small pocket of flint- 

 gravel in this chalk. 



The same description will apply also to the chalk which caps 

 the cliff cast of St. Lawrence. The Chalk Marl only is seen, but 

 it is possible that the tops of the hills touch the more massive 

 upper beds of the Lower Chalk. The base of the Chalk Marl 

 occurs in St. Lawrence Shuie and in the footpath leading up the 

 cliff to Whitwell. The dip is southerly and south-easterly at a 

 gentle angle. 



In the high down which extends northwards to Appuldurcombe 

 Park, there is a thickness of about 270 or 280 feet of chalk at a 

 point between Week Farm and Rew Farm, and. there must 

 therefore be from 60 to 70 feet of Middle Chalk on this hill, 

 underneath the gravel. Numerous old pits have been opened in 

 the Chalk Marl around Stenbury and Appuldurcombe Downs, and 

 a pit is now worked near Ventnor Cemetery, in a more massive 

 chalk, apparently the upper part of the Lower Chalk (the Grey 

 Chalk). Mr. Norman remarks that a portion of the head and 

 jaws of a laro;e fish was dug up in the Cemetery, but unfortunately 

 not preserved.* 



The junction of the Chalk Marl and Chloritic Marl is seen 

 on the brow of the cliff 900 yards east of St. Lawrence Shute, and 

 in the side of the zig-zag road leading up the cliff above the Royal 

 Hotel, Ventnor. It is exposed also in the cutting at Ventnor 

 Station, but is more accessll)le by the road-side, 150 yards east of 

 the Station, and in a road-side 300 yards east of St. Boniface 

 Well. 



St. Boniface Down forms the highest ground in the Island, 

 reaching a height 787 feet above Ordnance Datum. The base of 

 the Chalk on the north side of the Down is about 450 feet above 

 the sea, and on the south side about 300 feet, the distance across 

 being 1,.^20 yards. From these data it may be calculated that 

 the southerly dip amounts to I in 26^, or a little less than 2°, 

 — a result which agrees with that obtained in the tunnel (p. 72). 

 Fx'om the same data it may be calculated that the thickness 

 of chalk and gravel under the highest point of the Down must 

 be about 430 to 440 feet. But it will be remembered that 

 the united thicknesses of Middle and Lower Chalk at Culver 

 Cliff* amounted to only 386 feet. Above these there were 26 feet 

 of Chalk Rock and flintless chalk, making a total of 412 feet of 

 chalk below the lowest band of flints. If to this we add 20 feet 

 for the estimated thickness of flint-gravel on St. Boniface Down, 

 we obtain a total of 432 feet. It would seem then that, though 

 the lowest bed of the Upper Chalk may be present, there is not 

 room for any of the Chalk-with-flints, or at most for more than a 

 mere film of it beneath the gravel. 



* Geological Guide to the Isle of Wight, p. 99. 



