CHALK AND CEMENT. 83 



in the above-mentioned instance to the height of 200 ft. from 

 the bottom of the well. 1 



CHALK AND FLINT, WHITING, LIME AND CEMENT. 



The Chalk has been excavated by means of shafts at various 

 dates since Neolithic times, and for various purposes : to obtain 

 flint and chalk, or water, or to provide places of refuge and 

 storage. 



Thus, certain shafts 2 or 3 ft. in diameter have been sunk to 

 a depth of from 40 to 60 ft., and sometimes as much as 140 ft., 

 through Eocene strata into the Chalk; and, at the base, they 

 lead into simple or complex chambers. 



They are met with over a considerable area in North Kent 

 between Dartford Heath and Eltham, and from Abbey Wood 

 west of Erith to the uplands of Joy den's Wood (Stankey and 

 Cavey Spring pits) south of Bexley; indeed, about 200 

 shafts are reckoned to be present within an area of 6 by 

 4 miles. 2 



To these the name Dene-hole (meaning Dane-hole, not den- 

 hole) has been applied. They occur in numbers near together, 

 and yet are seldom connected below ground; and on this 

 account Mr. T. V. Holmes argues that they were made and used 

 rather for domestic purposes, as secret store-houses and hiding 

 places, than for the material extracted. 3 It is held that some 

 shafts may date back to Neolithic times, and were utilized by 

 the Romans as well as by the Danes. The vertebrate remains 

 found in the excavations, according to Mr. E. T. Newton, are 

 all of Neolithic or later date. 



We have no certain evidence in our area of shafts sunk to 

 obtain flints from the Chalk. In the well-known instances at 

 Grime's Graves and Cissbury, the shafts were wider than in the 

 case of the Dene-holes. 



In Hertfordshire and Buckinghamshire, ' wells,' for the 

 purpose of obtaining chalk to marl adjacent land, have been 

 sunk in old times, and also quite recently to depths of about 

 90 ft., and with a diameter of about 5 ft. ; and at the present 

 time chalk is obtained by shafts (80 to 150 ft. deep) and galleries 

 for use in the brickyards near Plumstead. 4 



In the much debated area of Chislehurst there is a complex 

 series of shafts and tunnels which have been shown on a plan, 

 constructed by Mr. T. E. Foster, to extend over an area of about 

 20 acres. 5 



1 ' Agriculture of Middlesex,' Ed. 2, 1807, pp. 27, 28, 35. 



2 Youens, E. C., Proc. Geol. Assoc., vol. xx, 1908, p. 458. 



Essex Nat., vol. xv, 1907, p. 10; see also vol. i, 1887, p. 225. Much has 

 been written on the subject also by F. C. J. Ppurrell and others. 



* Hayes, Rev. J. W., Nature, vol. Ixxviii, 1908, p. 375; Bennett, F. J., Essex 

 Nat., voL i, 1887, p. 260; and Leach, A. L., and B. C. Polkinghorne, Proc. 

 OeoL Assoc*. vol. xix, 1906, p. 345. 



5 Ward, T., Journ. Brit. Arch. Assoc., N.S., vol. *iii., 1907, p. 254. 



