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14

B E R K S H IR E .

obscured by landslips. As the name implies, the rock is
usually full of greenish grains. A t Woolstone it is 60 feet
thick, but above 100 at Didcot. The Upper Greensand
and the G au lt are now seen to be so closely allied as to
constitute really but one formation, to which the name of
S e lbo rn ia n has been given.
(3 )
W hite Chalk.— This is perhaps the best known
rock in England— lithologically speakin g; it constitutes
the central and most elevated portion of Berkshire. On the
west the main mass spreads across from Hungerford to
Compton Beauchamp, a distance of 12 miles. The strike,
or direction of the Chalk, is here nearly east and west and
continues so to the Tnames. The dip is to the south-east
at a very small angle, from one to three degrees only. In
the south the Chalk dips under the Tertiary beds of the
valley of the Kennet, and rises up further south at a sharp
angle along a line from Inkpen to Kingsclere (in H am p­
shire) ; at Inkpen Beacon the White Chalk attains an
elevation of 1,011 feet, the highest point reached by this
formation in the south of England. The total thickness in
Berkshire of this great mass of white soft limestone is pro­
bably over 700 feet, but some of the upper beds are want­
ing, having been eroded before the deposition of the Eocene
strata ; the Chalk was eminently a deep-sea deposit, for
when we examine it microscopically we find it to consist in
large part of the tiny chambered shells of foraminifera,
being very similar in composition, in fact, to the greyishwhite ooze which numerous soundings have proved to form
th e floor of the North Atlantic Ocean at the present time.
In the great mass of the White Chalk three main sub­
divisions are easily recognised— Lower, Middle, and Upper
— and each of these can be further sub-divided into Zones
(for details of which see the axtiele in this volume upon the
Geology of Bucks), which can, indeed, be traced and
recognised right across England, wherever the Chalk is
exposed.
(a.) 1 he Lower Chalk (total thickness, 215 feet) has
m arly beds at the base about 80 feet thick ; above these
come layers of grey to white chalk 135 feet thick, including
a hard band called the Totternhoe Stone.
This lower
division may be seen in the Great Western railway cutting
at Wallingford Road station.
(ft.) Ihe M iddle Chalk (total thickness, 170 feet). Above
the lower chalk, we get about 170 feet of chalk with few or
no flints, but containing m arly partings which indicate the
lines of bedding.
(c.) The Upper Chalk (total thickness 330 feet), is
characterized by the presence of flints, which occur most
frequently in small irregular lumps or nodules, but also in
fiat tabular sheets.
The origin of flints is still a vexed
question : m any appear to have been formed by the deposit
of siliceous m atter on and around organic bodies, such as
sponges ; the flat tabular masses of flint would seem to have
been deposited along the bedding-planes probably after the
consolidation of the rock. Such lines of flint m ay be seen
in the sides of the railway cutting near Pangbourn, and in
the chalk-pits at Courage, north of Newbury, and at Cookham Dean. Fossils are of frequent occurrence both in the
flint and the chalk ; sea-urchins or Echinoderras belonging
to such genera as Holaster, Marsupites, and Micraster,
abound, with sponges, belemnites, and such shells as
Terebratula, Inoceramus, &c.
The base of the Upper
Chalk is formed by a hard cream-coloured band—
the Chalk Rock— some 8 or 10 feet thick, which from its
superior hardness usually forms the top of the chief chalk
escarpment. Thus we can trace it all along the northern
brow of Ilsley Common and Childrey W arren; the Ridge
W ay runs along the edge, and sections are exposed at
Cuckham sley Knob, &c. The main mass of the Chalk passes
in Berkshire as far eastasRem enham ,W argraveand Maiden­
head, but Windsor Castle is built on an inlying boss,
probably elevated by some local disturbance ; the rock is
visible in the ice-house in the Castle grounds. Beds of
phosphatic chalk occur at Winterbourne and at Boxford.
They probably belong to the Marsupites-zone, and m ay be
the highest of the Chalk strata (in order of succession) ex­
posed in Berkshire.
The scenery of the Chalk Downs is very marked and dis­
tinctive. The beautifully smooth swelling hill-curves are
covered w ith a short dense herbage which affords good
pasturage for sheep and capital galloping grounds for
horses. The higher part of the chalk area is, however,
often covered with clayey* deposits, as south of llsley, and
then forms a soil on which the beech grows w e ll; but as a
rule the -wide open nature of the country is always dis­
cernible. The valleys are often waterless,' the rain being
soon absorbed by the porous soil. White Horse Hill rises
893 feet above the level of the sea. Economically regarded,
chalk is valuable as a dressing for clay lands ; much is also
dug to burn into lime, and it forms an ingredient of Port­
land cement. Whiting is solely made from chalk, Kintbury
being the seat of manufacture. The soft upper chalk is

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k e llv ’s

here ground into a pulp with water and allowed to settle
in tanks ; about 2,000 tons are made y e a rly ; it is mostly
sent to Bristol by canal, and fetches about 8s per ton.
Chalk was formerly more used for building than at present,
and when carefully selected is well suited for inside work,
being very easy to carve ; examples may be seen in Sonning
Town and in Tilehurst churches. The chalk-rock affords a
poor road-metal.
Flints furnish an almost everlasting
material for building ; they have been used with good
effect, dressed into a cuboidal form, in the beautiful little
church at Shottesbrook ; they are also ground up for use in
the manufacture of glass and porcelain.
T e r t i a r y P e r i o d : T h e E o c e n e S y s t e m .— A great
break in the succession of the rocks occurs at the top of th e
W hite Chalk. In the strata now to be described, which
rest directly upon the Chalk, we find the fossil remains of
animals altogether different to those which occur as fossils
in the Chalk, and we believe that there was a great interval
of time between the deposition of the two sets of strata,
during which either (1) 110 deposit was here formed, the
country having been raised above the sea-level and become
a land surface, or (2) deposits were formed which were
afterwards washed aw ay— denuded off— before the rocks of

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a T o u g h ferruginous
brow n clay . A t ab o u t
1<> inches from th e
I bottom there are ocoasional flattened concretion ary nodules of
clay iron-stone, about
three inches th ick , uuder a layer o f scattered
flin t pebbies (6) w hich
are fo r the m ost part
1 sm all and w hite.
c F erruginous brow n
sandy cla y or clayey
sand ab o u t fou r feet.
d B lack c la y ; v ery
hard and homogeneous, and s p littin g u p
w hen d ry v ery uneven­
ly w ith a so rt of conchoidal fracture, abo u t
three feet.

ro f e A line o f flin t peb'o ^q bles. A t th e ou tcro p
+= I th is bed form s a cono g < tinuous band o f cla y
^ = I iron-stone, fou r or five
PQ g I inches
th ic k ,
w ith
pq 1.sm all embedded flin ts.
< f Greenish
lo am y
. j clay
passing
dow nw ard s into more dec«pa 1 cided solid cla y a t th e
p*
| depth o f about th ree
(.feet.
Junction of Lon Ion Olay and W oolw ich and R eading Beds a t
K in tb u ry Brick-yard, north of P ebble H ill,
w h ic h w e n o w h a v e t o s p e a k w e r e l a id d o w n a s s e d im e n t
in se a s , la k e s o r r iv e r s ; p e r h a p s b o th t h in g s h a p p e n e d .
I . — L o w e r E o c e n e F o r m a t i o n . — ( 1 ) The Reading Beds
in Berkshire rest immediately upon the Chalk, anil were
formerly known as the “ Plastic C la y ; ” they consist of
alternations of clays and sands of many colours, with rolled
flint-pebbles.
Fossils are few, Ostrea bellovacina, which
much resembles the oyster of the present day, being the
only one found in any number. Commencing at Pros­
perous Wood, about two miles south of Hungerford, we can
trace these Reading Beds along the south of the River
Kennet to tivo miles east of N ew bury; on the opposite or
northern side of the river they continue nearly to Theale ;
then, after a gap formed by the connection of the Pang
with the Kennet, we find the same clays, sands &c.
spreading out east and west of Reading. Here they are
largely worked at Katesgrove, Coley Hill &c. The plastic
clays are made into tiles, drain pipes, &c. ; the sands aremixed with the clays in brick-making, or when white and
clean are used in glass works.
Thence the outcrop
continues about half a mile wide through Sonning and the
two Walthams towards Windsor. There are numerous out­
liers of the Reading Beds on the chalk hills north of the
Lambourn and the Pang, as at Beedon Hill, Basildon, and
Farnborough Copse. The junction with the Chalk below
is often marked by swallow-holes, which are caverns or
funnel-shaped pipes, into which the water, running down
the slope of the Tertiary beds, enters and disappears.

(2) The London Clay.— Where the junction of the London
Clay above with the Reading Beds below is exposed we see a
“ basement bed ” of blackish flint pebbles which are traversed
by cracks, so that they fall to pieces on receiving even a gentle