With the exception of a small tract in the south-western corner the
county is wholly drained by the river Thames and its tributaries;
that is to say, with a very few exceptions, every brook and stream
in Berkshire is more or less directly a tributary of the Thames.
The river Thames or Isis becomes the boundary between Berkshire
and Gloucestershire near Lechlade, and it flows in an easterly
direction over a clay country, keeping a little to the north of the
ridge of limestone hills upon which the villages of Buckland and
Hinton Waldrist stand. Near Appleton the river bends to the north,
curving round the outlying patch of limestone which forms Wytham
Hill, and being joined by the river Evenlode. The united streams
soon take a southerly course, and a little below Oxford are joined
on the north by the Cherwell. The river then crosses the limestone
formation near Sandford, and curves round by Radley to Abingdon. From
Abingdon the river pursues a somewhat serpentine course with a general
south-easterly trend towards Benson, being joined on the north near
Dorchester by the river Thame. A little south of Benson the river,
now the Thames proper, enters upon the chalk formation, across which
it flows in a southerly direction to Streatley, and then takes a
south-easterly course to Reading. At Streatley the river valley is
deep, with steep sides separating the chalk downs of Berkshire from
the chalk hills known as the Chilterns. The illustration above shows
the Berkshire downs in the distance and the valley of the Thames in
the foreground.
At Reading the Thames is joined by the Kennet, and it is interesting
to notice that the main stream adopts the direction of the tributary
and flows with a north-easterly course to Wargrave, near which place
the river Loddon meets it from the south, and again the direction of
flow of the tributary is adopted, the Thames taking a northerly course
past Henley. It is also of interest to observe that the river has
turned away from the soft clays which form the ground south and east
of Reading, and has cut a deep valley in the hard chalk from Wargrave
onwards. Beyond Remenham the course of the river becomes easterly,
and near Cookham it turns south and flows past Maidenhead to Bray.
Near Bray the Thames leaves the chalk over which it has flowed for
some 40 miles and enters upon a clay country, making its way in a
fairly direct line to Windsor, the one place in the district where a
knob of chalk sticks up through the clay. Windsor Castle stands upon
this knob of chalk. The course of the river from Bray to Windsor is on
the whole south-east, and after a big curve north at Eton the course
becomes more southerly, with another big curve near Old Windsor. At
Runnymede House the Berkshire boundary leaves the river, which flows
on to London and the sea.
The river Cole rises on the chalk not far from Ashbury, and flowing
in a northerly direction joins the Upper Thames or Isis at the extreme
western boundary of the county.
The river Ock rises on the chalk near Uffington, and flows down the
Vale of White Horse to join the Thames at Abingdon.
The river Pang rises on the chalk not far from Compton, and flows in
a southerly direction to near Bucklebury, where it turns eastward,
passing through a beautiful valley by way of Stanford Dingley and
Bradfield to a point near Tidmarsh. It then makes a sharp turn to
the north and joins the Thames at Pangbourne. This lower part of the
course of the Pang is worthy of study, for there is a continuous band
of river alluvium along the valley from the Thames at Pangbourne to
the Kennet at Theale. The source of the river, too, is well worthy
of investigation. In dry times it will be found in the valley near
Compton, but in wet seasons it is much further up in a branch valley
towards East Ilsley.
The Lambourn also rises on the chalk near the place of that name,
and it flows in a south-easterly direction and joins the Kennet close
to Newbury. The Pang and the Lambourn flow in chalk valleys for the
whole of their course.
The river Kennet rises in Wiltshire, enters Berkshire near Hungerford,
and flows with an easterly course by way of Kintbury, Newbury, and
Theale, finally joining the Thames close to Reading. It is a chalk
river, and obtains a considerable amount of water from springs in
the valley along its course.
The Emborne is not a chalk stream. It rises in the Inkpen district
and flows in an easterly direction, forming, as we have seen, the
county boundary for a considerable distance. Its course is almost
parallel to that of the river Kennet, the two valleys being separated
by hills or plateaux of clay, sand, and gravel. Near Brimpton the
Emborne turns sharply to the north-east, and joins the river Kennet
near Sulhampstead Bannister.
The Foudry Brook rises in a clay district of Hampshire, not far from
Silchester, and runs by way of Stratfield Mortimer and Grazeley to
the river Kennet near Reading. It is a small stream now, but there
is a good deal of alluvium along its course, showing that it was of
more importance in former times.
The river Loddon rises in Hampshire and enters Berkshire at the edge
of Strathfieldsaye Park, its direction being northerly. Soon, however,
it turns to the north-east and flows in a tolerably straight line to
join the river Thames near Wargrave.
The Blackwater rises near Aldershot and reaches Berkshire at Blackwater
Bridge, where, as we have said, the counties of Berkshire, Hampshire,
and Surrey meet. From this point the river flows in a north-west or
west direction and forms the Berkshire boundary for eight miles to a
point near Little Ford below Farley Hill. The Blackwater then turns
into Berkshire, running in a north-westerly direction to Swallowfield,
where it joins the river Loddon.
There are no natural lakes in Berkshire, though there are the deposits
of a former lake in the valley of the Kennet near Newbury.
There was formerly a sheet of water near Twyford named Ruscombe Lake,
which had some claim to be called a natural lake, in that it was a
low-lying bit of ground which was flooded owing to the absence of a
good outlet. Its natural outlet was into the river Loddon, and there
is a patch of alluvium extending from its site through Stanlake Park
to that river. It was eventually drained by making a deep channel
called the "Cut," draining a considerable area into the Thames near
Bray. It has been asked why the river Thames did not follow the line of
Ruscombe Lake and the Bray Cut, all soft clayey soil and low ground,
instead of cutting the great and deep valley through the chalk by way
of Wargrave, Henley, Great Marlow, and Maidenhead. The explanation
probably is that the river Thames existed before any of these valleys,
and that its course was determined by local features which have long
since been destroyed by rain and streams, and by the river itself.