Reviews— Codrington’s Berks‘and Hants, §c., Railways. 505 
which Mr. Codrington gives a figure. His descuiptiowe however, 
might well have been fuller, as he does not give the composition of 
the ‘Chloritic Marl,’ or the ‘Upper Greensand’; nor does he tell 
us whether he classes the former with the latter, or with the Chalk. 
Another cutting, at Tinkfield, showed a mass of drifted Greensand, 
just like the same in place, but overlying peat, which in its turn was 
underlain by chalky mud, the whole filling a hollow in the Upper 
Greensand. A list of Upper Greensand fossils, showing the species 
found in six different places, ends the account of this railway. 
The Marlborough Railway is a branch or offshoot of the above, 
and its cuttings are in Chalk, capped sometimes by some of the 
surface-beds peculiar to that rock. The first, at Lye Lane, is 
‘through part of the Lower Chalk, here consisting of hard, thick- 
bedded stone,’ with fossils. May not this be the representative of 
the Totternhoe stone and marl (Chalk-marl) of Buckinghamshire 
and Bedfordshire,* and of the Grey Chalk between Dover and Foike- 
stone ? 
The Lye Hill cutting is in higher beds, and shows the junction 
of the Lower and Upper Chalk, here marked by the presence of 
the ‘ Chalk-rock,’ a hard bed, 10 feet thick, very constant in its 
occurrence, and, from its greenish-yellow colour, easily recognised, 
and which has been traced by the Geological Survey from this 
district for many miles north-eastward. Mr. Codrington says that 
‘about four feet below the Chalk-rock there is here a succession of 
irregularly-shaped cavities, filled with a brown sand, probably of 
Tertiary age, which has found its way through the Chalk-rock from 
its outcrop on the surface, and not through it in sand-pipes’; and 
he thence infers that ‘the Chalk here appeared to have suffered 
considerable tilting-up and denudation before the deposition of the 
Tertiary beds ; otherwise sand of the latter age could hardly have 
penetrated into the Lower Chalk.’ With this we cannot agree. In 
the first place, what is the proof that the sand belongs to the Reading 
Beds, which in this district overlie the Chalk ? and if so, what is 
the proof that it has not found its way down through pipes, the 
higher parts of which no longer exist, but have been destroyed by 
denudation ? and we know that such remains of pipes do occur. The 
notion of such an erosion of the Chalk, before the deposition of the 
old Tertiary beds, is at variance with all that we know of the junction 
of those formations in England, and is quite opposed to the fact that 
in this very neighbourhood, as elsewhere, the Tertiary beds and the 
Chalk are alike affected by the same disturbances. 
In the cutting, in the Chalk-with-flints, there is mostly at the top 
‘a drift of re-arranged Tertiary beds,’ as Mr. Prestwich has noted in 
one of his well-known papers. ‘ This drift is principally the deposit 
called “Clay-with-flints” by the Geological Surveyors, and is covered 
in places by clayey sand or Brickearth.’ Mr. Codrington’s descrip- 
tions and figures of these beds agree with what has been published 
about them by the Geological Survey. ‘The surface of the Chalk is 
* See Grotocican Macazinu for May, 1865, p. 215. 
