NOTES ON ESSEX GEOLOGY. 275
as perhaps "part of an old glacial lake deposit," and is "led
to the conclusion that the greater features of the Thames valley
were formed before the climax of the Ice Age." But he adds
that "there can be no doubt that much denudation of the
Cretaceous and Tertiary formations was effected by the Thames
and its tributaries long after the dissolution of the ice sheet."
The various gravel-terraces are noticed and their formation
discussed
Chapter xxxviii. of Jukes-Browne's Cretaceous Rocks of
Britain, vol. ii.,22 treats of the Middle Chalk of Cambridgeshire
and North-east Essex ; but the references are all to the former
county. Clearly there is here an opening for observers. There
is an error in the Index, where Essex is credited with something
on p. 193.
What is presumably the best general account of the geology
of Essex (up-to-date), was given by our Honorary Member,
H. B. Woodward, in the Victoria History of Essex. In this
essay the author discusses the question whether Coal Measures
occur at a workable depth, but wisely refrains from giving a
definite opinion. I take this chance of recording the loss to
geology from the death of my old friend and erstwhile colleague
in February of this year.
A short account of the Palaeontology (Vertebrates only)
is given by R. Lydekker, and under Early Man the Palaeolithic
Period is noticed.23
1904.
Dr. A. Irving, in dealing with "Plateau Gravels on the North
Side of the Tamisian Area,"24 supplements former papers.
He notices the rock-constituents of the gravels, the chief
characteristic of which is the abundance of quartzite-pebbles,
etc., from the Bunter of the Midlands. "Not only are these
gravels much older than the Boulder-clay. . . superimposed
upon them, but their relation to the present river-drainage shows
that they are older than even the pre-Glacial valleys of erosion
in the Chalk." This argument may hold if the Glacial infilling
of those valleys is not older than the Boulder Clay, as has been
suggested of late years.
I must own to being staggered by the author's reference
22 Ment. Geol. Survey.
23 Vol. i., pp. 1-23, Geological Map, pp. 25-30, pp. 261-263, plate of implements.
24 Geol. Mag., dec. v., vol. i., p. 497.