38 
THE CRETACEOUS ROCKS OF BRITAIN. 
glauconitic sand-rock, for the proportion of marly matrix is small, 
but sufficient to bind together the sandy ingredients into a coherent 
mass. Its base is piped into the underlying Gault—that is to say, 
the top of the Gault is penetrated by a number of small and irregular 
pittings and borings which are 3 or 4 inches deep and are filled 
with the material of the overlying sand. There are no phosphate 
nodules at the junction, nor are there any higher up in the bed. 
Upwards the proportion of sand diminishes and that of the marly 
matrix increases, but it continues to be distinctly green and sandy 
for a distance of about 16 feet, when it shades off rapidly into the 
next bed (2). The upper part is a green, sandy glauconitic marl 
with irregular spots and veinings of whiter marl. It it sufficiently 
coherent to weather along vertical joints into blocks of irregular 
prismatic shapes. 
From the constant slips it is not easy to measure the thickness 
of this bed, but it is best exposed below the small outlier of Chalk 
Marl on which Martello Tower No. 3 stands, fir. Fitton estimated 
its thickness here as “ about 14 feet; ”* Mr. Topley thought that 
“ it may be 15 feet thick ; ”f Mr. Price, describing it in 1877, says 
it is about 14 feet,J but that “ it is extremely difficult to obtain 
an accurate measurement.” Mr. It. Kerr, chanced to have 
a good opportunity of measuring it in 1887, and found it to be 
16 feet. 
Fossils are not abundant in this bed, but the two sponges Stauro- 
nema Garteri and Plocoscyphia lab rasa and the bivalve Avicula 
gryphceoides can generally be found. Ammonites [Schloenbachia] 
varians and Scaphites cequalis have been found, but are rare. Pecten 
asper has never been found. 
This bed was formerly regarded as a representative of the true 
Upper Greensand, and was treated as such in Mr. Topley\s Geology 
of the Weald (1875), and by Professor Barrois in his Kecherches 
sur le Terrain Cretace (1876, Table, p. 168). In 1877, however, 
Mr. F. G. PI. Price dissented from this view, and wrote as follows : — 
“ Upon carefully examining this bed, in company with Ur. Charles 
Barrois, of Lille, I have come to the conclusion that the Upper 
Greensand is wanting in the south-east of England (unless it be 
represented paleontologically bv the Upper Gault, Beds X. and 
XI., zone of Ammonites rostratus), and that the dark green sandy 
deposit just now described forms the basement-bed of the Chalk 
Marl, they being paleontologically the same.” (Op. cit., p. 436.) 
In 1878 Professor Barrois also expressed his change of view; he 
separated its equivalent in France from the zone of Pecten asper 
and called it the zone of Ammonites laticlavius. He remarks, “ this 
zone of Am. laticlavius corresponds exactly with the bed which I 
have followed throughout England under the name of Chloritic 
* Trans. Geol. Soc., Ser. 2, Vol. iv. p. 107, 1836. 
t Geology of the Weald, p. 152. Mem. Geol. Survey, 1875, 
X Quart. Journ, Geol, Soc., VqL xxxiii. p. 433, 1877, 
