to represent the original overflow of the river.

At the crossing places (as we shall see later), notably at Long
Wittenham, at Wallingford, at Streatley, at Pangbourne, and, still
lower, at Maidenhead and at Ealing, this hard soil came right down to
the bank upon either side.

On all this lower half of the Thames marsh was rare, and was to be
found even in early times only in isolated patches, which are still
clearly defined. These are never found facing each other upon opposite
banks of the stream. Thus there was a bad bit on the left bank above
Abingdon, but the large marsh below Abingdon, where the Ock came in,
was on the right bank, with firm soil opposite it. There was a large
bay, as it were, of drowned land on the right bank, from below Reading
to a point opposite Shiplake, the last wide morass before the marshes
of the tidal portion of the river; and another at the mouth of the
Coln, above Staines, on the left bank, which was the last before one
came to the mud of the tidal estuary; and even the tidal marshes were
fairly firm above London. From Staines eastward down as far as Chelsea
the superficial soil upon either side is of gravels, and the long list
of ancient inhabited sites upon either bank show how little the
overflow of the river interfered with its usefulness to men.

The river, then, from Sandford downward has afforded upon either bank
innumerable sites upon which a settlement could be formed. Above
Sandford these sites are not to be found indifferently upon either
bank, but now on one, now on the other. There is no case on the upper
river of two villages facing each other on either side of the stream.
But though the soil of this upper part was in general less suited to
the establishment of settlements, a certain number of firmer stretches