58 THE CRETACEOUS ROCKS OF BRITAIN. 
is now called Lower Chalk, and the three parts are thus described : 
“ The base of the series is composed of a loose, pale grey marl with 
beds and concretions of a harder substance, and in some parts it 
is quite of a blue colour. Above it a white marly chalk, resembling 
Upper Chalk, is overlain by a very hard dark green marl which 
is quarried at Wilsham.” Wilsham is the name of a small hamlet 
half a mile east of Alton and just below the outcrop of the Melbourn 
Rock ; there are old quarries there, and thus it seems most prob¬ 
able that the dark green marl seen by Mr. Curtis was the zone of 
Actinocamax plenus. If so, the succession which he describes is a 
perfectly correct one, and is true for the whole of Hampshire. Pro¬ 
fessor Barrois who visited Alton and the neighbourhood in 1875, 
formed the same idea of Mr. Curtis’s observations, and added some 
notes of his own. * 
The Main Outcrop. 
Zone of Ammonites varians. 
Chloritic Marl. — The existence of a phosphatic bed at the base 
of the Chalk in the north of Hampshire was first made known bv 
Messrs. Paine and Way in 1848.f They describe it as a bed 
about 3 feet thick, consisting of a green marl more or less siliceous 
( i.e ., sands), and abounding in organised fossil remains. The fossils 
were not evenly dispersed throughout the stratum, “ but often 
lie in most irregular heaps ; ” their principal constituent is phos¬ 
phate of lime, and the marl itself, even when the fossils and 
nodules have been sifted out, often yields on analysis from 10 
to 15 per cent, of phosphate of lime. 
In their exploration of the bed they describe it as occurring 
on the north-west side of Farnham below the Castle, and running 
in a W.S.W. direction through Beaver’s Hill and the central part 
of Dippen Hall Farm, and thence to Bentley. From Bentley 
“ the phosphoric band, proceeding in a south-west direction, may 
be traced to Froyle, in which parish it crosses the Southampton 
road; it then continues with the same bearing till it crosse-s the 
River Wey below Alton, and is traceable, though occasionally much 
obscured by diluvial detritus, to Worldham. Here there is an 
immense longitudinal quarry about 15 feet in depth, from which 
at some remote period thousands of loads have been removed.” 
With respect to the phosphatic nodules themselves, they describe 
them as of three kinds. The first includes fossils of various sorts, 
fine specimens “ of the siphonia pyriformis and of other alcyonites 
are profusely abundant,” together with “ quantities of large amor¬ 
phous spongoid bodies, which possess a general uniformity of 
structure.” They also found a peculiarity in this class of fossils, for 
not only do they differ greatly from each other in chemical com¬ 
position, and especially with respect to the amount of phosphate 
of lime they contain, but they also vary in their own component 
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* Recherches sur le Terr. Cret. Sup., 1876, p. 44. 
f See Journ. Roy. Agric. Soc., Yol. ix. p. 75, and Yol. xii. p. 544. 
