250
THE ESSEX NATURALIST.
same line may well have been followed at an earlier date, when
the Rayleigh gravels were accumulated by an ancestor of the
Medway, and it is probable that an extended Crouch drained
the trough in later times.
The evidence for such a course is strong, but only when con-
sidered in relation to the surrounding regions. A glance at the
map will show that there are only two other possibilities :—
(a) That the Winter Hill Thames followed roughly the
present course, and hence that all traces of it have been lost
in later base-levelling. This hypothesis confronts the over-
whelming objection that there is no means of testing it and it
will, we think, find few supporters.
(b) That the Winter Hill Thames passed up the line of the
lower Lea valley, and thence eastwards along the broad depres-
sion, now covered with boulder-clay, which separates the hills
around Brentwood and Billericay from the high ground around
Hatfield Broad Oak. Against this view we have the fact
already noted that the floor of the depression (beneath the
boulder-clay) is at about 200 ft. O.D., too great an elevation to
accommodate the Winter Hill terrace, or its equivalent, which
passes below 200 ft. somewhere between Iver and Wimbledon.
This northern depression has some claim to be regarded as an
even earlier route of the Thames, but this question we must
leave unexamined here. The greatest interest must at present
attach to the phase in the evolution of the Thames which preceded
that of the Boyn Hill terrace.
As regards the precise date of the Winter Hill stage the
evidence is, in some degree, conflicting, but it seems likely that
it represents the interglacial episode which preceded the advance
of the Chalky-Boulder Clay ice ; but in the absence of faunal
evidence, no certainty can be gained on this point and we must
be content to leave the matter an open question until further
facts are to hand.
Bird Protection Order.—The Borough of Southend-on-Sea has
obtained an Order giving protection all the year through to Goldfinch,
Chaffinch, Lark and Linnet.