CIIAI.K. 75 



The cliffs of flinty Chalk at the two ends of the Isle of Wight are 

 among the finest to which this foniiation gives rise in the British 

 Isles. The brow of the part known as the Main Bench, near the 

 Needles, which is vertical and descends sheer into the water, was 

 determined by the Ordnaace Survey to be 416 feet above the 

 datura-level, while the Grand Arch, which forms the east side of 

 Scratchell's Bay and overhangs considerably, is 300 feet in height. 

 It will be noticed that the flinty chalk alone is capable of forming 

 these vertical or overhanging cliffs. Both here and at Culver, 

 wherever chalk without flints rises next the sea, there is a beach 

 of chalk blocks, and a more or less accessible slope at the foot of 

 the cliff.* It is in the Chalk-with-fiints also that the numerous 

 caves of the neighbourhood of Freshwater, the Needles, and the 

 extreme point of Culver Cliff, have been excavated. 



In the Chalk of the Isle of Wight the following sub-divisions 

 are recognisable. The thicknesses of the Middle 'and Lower 

 Chalk have been obtained by direct measurement in Culver Cliff, 

 that of the Chalk- with-flints by estimation. 



Feet. 



{Chalk-with-flints, about - - 1,350 



Chalk, nodular, but without flints - 15-25 

 Chalk Rock, a line of green-coated 

 nodules. 

 ["Thick-bedded chalk, with thin partings 

 M'lll CI 11' J of marl _ - _ . iqq 



"1 Nodular chalk (? Melbourn Rock) and 

 (^ marl (? Belemnitella Marl) - - 14 



r Massive chalk - - - 86 



Lower Chalk ■< Thin-bedded chalk and marl in 



(^ numerous beds - - - 120 



Chloritic Marl - - - 7-15 



The principal sub-divisions were first recognised by Mr. Webster 

 in 1812 (Sir H. Englefield's Isle of Wight, p. 236). He used the 

 names Chalk with Flints, Chalk without Flints, and Chalk Marl. 

 The Chalk without Flints, he remarks, " differs from the former 

 only in the absence of flints, in the beds being thicker, and the 

 chalk being sometimes a little harder." The Chalk Marl is 

 described by him as consisting " of chalk and an intimate mixture 

 of clay .... It may be readily distinguished from chalk 

 by its falling to pieces on being wetted and dried again." 



In 1865 Mr. Whitakerf identified a line of green-coated 

 nodules, occurring some 8 or 10 feet below the lowest course of 

 flints, as the representative of the bed which he had previouslv in 

 Berkshire named " Chalk liock," and had taken as the topmost 

 bed of the Lower Chalk, i.e., of the Middle Chalk of the above 

 table. 



* The coast from the Needles to Freshwater can be examined by boat only. The 

 point on the east of Freshwater Bay and that of Culver Cliff can rarely, if ever, be 

 passed on foot. 



f Quart. Journ. Geol. Soc, vol. xxi. p. 400. 



