CHALK. 417 



ness from two to fifteen feet. This neighbourhood is celebrated 

 for its hop-gardens.^ 



Much of the Chalk around Basingstoke, Mitcheldever, and 

 Andover has but little soil and forms bare and open ground. 

 Northwards the anticlinal structure of the beds at Kingsclere and 

 Highclere tilts the Chalk to a high angle, as at Guildford, and 

 brings the Upper Greensand to the surface in a so-called "Valley 

 of Elevation." (See Fig. 63, p. 382.) The Chalk too in this 

 neighbourhood attains, at Inkpen Hill, its highest elevation in 

 England (nearly 1000 feet). A fine section of Upper Chalk is 

 exposed at Paul's Grove Pit, Portsdown Hill, near Portsmouth. 



In the Isle of Wight the chief palaeontological divisions of the 

 Chalk have been determined by Dr. Barrois.' (See p. 403.) In 

 the fine cliffs at Culver, on the east side of the island, the Chalk 

 dips at a very high angle, and on the opposite side, at Alum Bay, 

 it is nearly vertical. (See Fig. 73.) The main features in the 

 geology were noted many years ago by Sir Henry C. Englefield 

 and j\Ir. T. Webster.^ 



Mr. C. Parkinson regards the Chloritic or Glauconitic Marl as a distinct bed in 

 the Isle of Wight. It may be traced immediately over the Upper Greensand, along 

 the Undercliff, from Blackgang chine to Luccombe chine, and again near 

 Culver cliff. He observes that it varies in thickness from 6 to 7 feet, and 

 may be divided into two beds separated by a layer of phosphatic nodules. 

 The best sections are at Ventnor Station quarries and below Old Park, St. 

 Lawrence. He proposes to call it the "zone of Turrilites AIo>-risii," rather than 

 the zone of Scaphites cequalis.^ 



SOUTH-WEST OF ENGLAND. 



In Wiltshire and Dorsetshire the total thickness of the Chalk is 

 about 800 feet. It forms the Marlborough Downs and Salisbury 

 Plain, extending westwards to the hills near Mere. The Chalk ]\Iarl 

 (rich in Ammonites) varies in thickness from twenty to fifty feet. 

 Ammonites Wiltoncnsis was obtained by Mr. W. Cunnington from 

 the hard chalk of Devizes; the Pewsey cup-corals, Parasmilia 

 cultrala, are also met with in that neighbourhood. The Chloritic 

 Marl is sometimes six feet thick; at Wroughton, near Swindon, this 

 phosphatic bed is eighteen inches thick. The Chalk Rock has 

 been observed near IMarlborough. 



From Salisbury the Chalk extends by Cranborne Chase to 

 Blandford, Bere Regis, Piddletown, and around Dorchester and 



1 Godwin- Austen, Q. J. iv. 257 ; H. W. Bristow and W. Whitaker, Geol. of 

 parts of Berks and Hants (Geol. Survey), p. 12. 



^ Recherches, etc. (see p. 401), and Ann. Sec. Geol. du Nord, vi. 10 ; see also 

 H. W. Bristow, Geol. Isle of Wight (Geol. Survey), and W. Whitaker, Q.J. 

 xxi. 400. 



3 Englefield, Trans. Linn. Soc. 1802 ; see also his Description of the picturesque 

 beauties, etc., of the Isle of Wight, 1816, with notes and sketches by T. Webster; 

 also T. G. S. ii. 161 ; and Alantell, Geol. Excursions round the Isle of Wight, 

 edit. 3, 1854. 



* Q.J. xxxvii. 372. 



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