COAL MEASURES BENEATH ESSEX.
141
of all the borings in the London Basin (using the term in its wider
sense) in which Palaeozoic rocks have been reached. They are ten
in number, as follows : Culford (Suffolk), Ware. Cheshunt, Kentish
Town, Meux's Brewery (London), Crossness (Kent), Streatham
(Surrey), Harwich, Dover, Richmond. Not much new light after
all is thrown upon the question under consideration, since the
results of all these borings were generally known to geologists. A
gleam of light perhaps is gained from a consideration of the limited
distribution of the Jurassic strata under the London Basin. So
far as these borings can tell us anything, we can infer that (making
all allowance for a certain amount of denudation) the arm of the
Jurassic sea was co-incident with a line of synclinal flexure lying to
the north of the westward extension of the Ardennes axis through
the area of the Weald, as indicated in my article, and that in this
trough the coal measures of Dover had been let down, since it is
precisely along such a belt of country that the Jurassic strata are
found immediately overlying the Palaeozoic rocks at Richmond,
Streatham, New Oxford Street, and Dover.
" As we advance northwards, however, we lose touch of the
Jurassic series altogether, and, so far as the borings can tell us,
enter upon a region of Palaeozoic strata, which in all probability was
a land-surface during the long period of time represented by the
Triassic and Jurassic formations. This is a simple inference from
the fact, that in the borings at Kentish Town, Cheshunt, Ware,
Harwich, and Culford, we pass at once from the Cretaceous strata
into those of the Palaeozoic series. Earth-movements in this area,
about the beginning of the Cretaceous period, led to the submergence
of the land-area indicated above, so that the Cretaceous sea spread
over the whole of the south-east of England ; just as earth-move-
ments on a grander scale led to the submergence of the Bohemian
area, and the deposition of strata of Cretaceous age upon the older
Palaeozoic and Archaean rocks of that region. All this lends
emphasis to what was said in my article as to the significance of the
absence of Triassic and Jurassic rocks in all the East Anglian
borings. That the region of elevation in the East Anglian area
during Triassic and Jurassic time was of the nature of an axis
trending approximately to the north-east, is a hypothesis (as I before
pointed out) favoured by the penetration of crystalline rocks beneath
the Jurassic at Bletchley, and of the Carboniferous, at Northampton,
beneath the Trias. The paper just published contains information
which tends to strengthen that view, as 'further north, at Yarmouth,
Norwich, Holkham, and Lynn, such (Palaeozoic) rocks have not
been reached by borings taken to a deeper level than that at
Culford.' This would lead us to suppose that the axis of elevation
of the older rocks trends more to the east than was suggested in my
article above.
" The few additional facts here indicated make the probability
of the existence of Coal-measures beneath north-western Essex