ON THE 
Occurrence of the “Chalk Rock” near Salisbury, 
By Wittram Wuairarer, B.A., (Lond.) 
Of the Geological Survey of England. 
NN 1861 a bed was described, under the name “ Chalk-rock,” 
which, in the counties of Wilts, Berks, Bucks, Oxon, and 
Herts, seemed to form the top of the Lower Chalk.! Its occur- 
rence in the Isle of Wight, though in a less marked form, has since 
been noticed;? some new sections in North Wilts have been described 
in the Wiltshire Society’s Magazine by my friend Mr. T. Codrington,’ 
and I have also seen it in Bedfordshire* and Dorsetshire. As it is 
open to view near the town (Wilton) where the Society is to hold 
its meeting this year (1870), a description of two sections in that 
neighbourhood may perhaps be acceptable. 
The Chalk-rock, where best developped (from near Marlborough to 
near Henley-on-Thames) is a hard somewhat crystalline cream- 
coloured chalk, ringing when struck with the hammer, jointed, and 
with layers of irregular-shaped green-coated nodules. Sometimes 
however it consists simply of one hard nodular layer. 
In the cutting on the South Western Railway just north-east of 
Barford St. Mary (west of Salisbury), there is a good thickness of 
the Upper(or flinty) Chalk, the flint occurring both in the form of 
nodules and of thin tabular layers. From below this the Lower- 
Chalk (which here contains a few flints) rises westward at a very 
small angle: it is hard and of a somewhat nodular structure, and at 
(or close to) the top has a layer of green-coated nodules. This hard 
nodular layer is the bed to which I wish to draw attention, not only 
1Quart. Journ. Geol. Soc., vol. xvii, p. 166. See also Geological Survey 
Memoirs on Sheet 13, p. 19 (1861) and on sheet 7, p. 5 (1864). 
2 Quart. Journ. Geol, Soc., vol. xxi, p. 400. 
8 Vol. ix, p. 167. 
4Mr, J. Saunders, whose notice I called to this bed, has described a section 
near Luton, Geol. Mag., vol, iv, p. 154. 
