Kellys_Berks_Bucks&Oxon_1911_0017.jpg

15

B E R K S H IR E .

D IR E C T O R Y .]

blow : they are embedded in a brownish loam ; above this are
sandy clays passing up into stiff blue and brown c la y ; this
formation has a broad outcrop in Berkshire. There is a
good section in Shaw brick-kiln, north of Newbury.
Eastwards of Reading these clays occupy a district
gradually widening from 3 or 4 to 10 or 15 miles in
breadth, over which are scattered large outlying masses of
rocks presently to be described. Brick-yards and railway
cuttings afford almost the only sections of the London
Clay, as at Sonning, Windsor, Englefield, Frilsham &c.
Pectunculus decussatus and D itr v p a p la n a are characteristic
shells.
I I , — U p p e r E o c e n e F o r m a t i o n :— The B a y shot Beds.
The Bagshol Beds are sandy, forming ranges of barren
heath-covered hills in the south and south-east of the
county : sections and fossils are equally ra r e : they form
the high grounds of Coldash and Bucklebury Commons,
north of the K en n et: south of that river they extend from
Inkpen Common by Greenham Heath to the commons ot
Tadley, Silchester and Burghfield ; then we come to the
valley of the Loddon, where the beds have been denuded.
Crossing this gap we find ourselves on the western end ot
the main Bagshot mass near Finchampstead and Woking­
ham, and it continues by Ascot race-course to Egham 111
Surrey : south of this line we pass over some clayey beds,
known as Middle Bagshot or Bracklesham Beds, and
ascending Easthampstead Plain find ourselves standing
upon the northern extrem ity of the well-known Chobhain
Ridges, formed of the loose Upper Bagshot Sands.

Winkfield, a place three and a half miles west-south-west of
Windsor Castle ; the strata passed through w ere: London
Clay, 136 fe e t; Reading Beds, 78 feet; Upper Chalk, 329
feet; Chalk Rock, 8 feet; Middle Chalk, 169 feet; Lower
Chalk, 219 feet; Upper Greensand, 31 fe e t; G au lt, 264
feet - and Lower Greensand, to 9 fe e t: Total Depth, 1,243
feet. A plentiful supply of soft water was obtained from
the Lower Greensand, and though the water contained a
little common salt, it was barely sufficient to affect even the
most delicate palate.
S u r f a c e D e p o s i t s . — Our examination of the strata at
any point is often interfered with by the presence of beds
of gravel, brick-earth &c. m any feet thick, which cover over
and hide the underlying rocks. The Chalk, for example, is
often covered with a stiff brown and red clay full of unworn
flints. This would seem to be (in part at least) the residue
left by the removal of the carbonate of lime from the
Chalk', by the chemical action of rain-water charged with
carbonic acid ; this “ clay with flints ” is well seen in the
road cutting south of Remenham. Another possible origin
of this surface deposit is th at it is a surviving remnant of
the Reading Beds, which contain clays somewhat similar 111
character. Of brick-earth there is not much ; some m ay be
seen near Cookham.

The Flint-Gravels occur at high levels, as at Pebble Hill»
south of Kintbury, and often capping the hills of Bagshot
j Sand ; or at low levels, as from the foot of Enborne Hill to
Newbury, and on both sides of the Thames.
I

G ravel-pit on Inkpen Common, show ing the “ h igh -level g ra v el,” composed of sub-angular flints.

a W hite an g u lar flint g ravel.

b Brow n flin t g rav el, co n tain in g larg e blocks of g rey-w eth er sandstone.

Standing here on the latest formed of the stratified rocks
which constitute the county of Berks, we should, in
imagination, sink a deep borehole and picture it to ourselves
as passing in succession through all the beds of rock we
have named until, at a depth of perhaps 2,500 feet, it
entered the identical formation— the Oxford clay— which
we found occupying the surface of the county in the north­
west corner near Buscot.
A well sunk at Wokingham passed through London Clay,
263 fe e t; Reading Beds, 54 fe e t; Sand 16 fe e t ; and
pierced the Chalk for 64 feet, obtaining a good supply of
water from the last-named rock.
G r e y - w e t h e r s o r S a r s e n S t o n e s . — Blocks of a hard
sandstone are frequently found on the surface of the Chalk,
&c. ; the}' are used for building and for mending roads.
They would appear to be consolidated masses of either the
Reading Beds or the Bagshot Sands, which have been let
down and left behind, as it were, by th e washing away of
the looser m atter in which they were once embedded (see
section of gravel-pit given below). The Sarsens produce
good road metal and an excellent building stone ; Windsor
Castle, indeed, is built of this material.
D e e p B o r i n g a t W i n k f i e l d . — Since the introduction of
the “ Diamond Boring Machine,” about the year 1870,
many boreholes have been put down in different parts of
England (mostly in search of either coal or water), to depths
exceeding, in a few cases, even 3,000 feet. Of such bore­
holes, the only important one, as regards depth, hitherto
executed in Berkshire was made in 1894, for water, at

e L o w er B agshot Sand.

Alluvium .— In former times the river Kennet deposited
m uch mud for about a quarter of a mile on either side of its
present course : this now forms valuable water-meadows,,
always green. Beds of peat occur in it, from 5 to 15 feet
thick ; this peat is largely dug at Newbury, and when burnt
the ashes form a valuable fertilizer, probably from the
quantity of gypsum they contain.
In the museum of the Newbury
Institution, there is a fine speci­
men of the skull and horns of
Bos primiyenius, a large extinct
species of ox, which were dug out
of the peat in Ham Marsh. In
a large excavation close to Read­
ing a fine section of old rivergravels and loams is exposed, in
which Prof. E. B. Poulton has
found trunks of trees and bones
and teeth of such extinct animals
as the mammoth, the woolly rh i­
noceros &c.
E c o n o m ic G e o l o g y . — Likestem m ed
and barbed the other counties bordering the
F lin t arrow -h ead , fou n d in Thames, Berkshire is not noted
a burial-m ound on L a m -' for itg mineral wealth: th e
now fu1“t B r f t f f h M S u m

mottled plastic clays of the.Reading Beds are, however, largely
worked for brick-m aking. The following figures for the
year 1909 are extracted from Mines an>l Quarries, but they
do not include any excavations which are less than 20 feet
in depth.