206
GEOLOGICAL NOTES.
Street terrace or to an older one, the slight valleys worn in the
gravelly plain to the underlying London-clay tend much to
obscure its nature and real elevation, when viewed from a point
between Ley Street Station and the Cran Brook.
Beyond the Cran Brook northward, there are, as already
mentioned, no cuttings for a distance of more than two miles.
The next begins in a field on the more southerly side of Manor
Road, between Grange Hill and Frog Hall, where the line
begins to turn westward. North of Grange Hill Farm there is a
tunnel about 270 yards long, westward of which is an open
cutting as far as Newbarns Lane, west of the road between
Chigwell and Woodford Bridge. Beyond the spot at which the
line crosses Newbarns Lane are the marshes of the Chigwell
Brook and the Roding which are traversed by means of an
embankment. And the slight cutting close to the junction with
the Loughton line is too shallow to afford anything of geological
interest.
Between Manor Road and Newbarns Lane the cuttings and
tunnel are in London-clay. But here and there west of the
tunnel there are many pebbles on the surface of the clay,
especially near the spot at which the Hainault Road crosses the
line. The new railway here touches the northern boundary of a
patch of gravel which is shown on the map of the Geological
Survey (1. N.W. drift edition) as existing mainly south of the
line and between the Hainault and Chigwell Roads. It is
coloured as old river gravel, and is about a mile north-west of
the gravel of Fairlop Plain and fifty or sixty feet higher in level.
It would, therefore, appear to be of more ancient date than that
of Ley Street and Fairlop Plain, and of less antiquity than the
glacial gravel north of Chigwell. The railway cutting, however,
does not afford any good sections in this gravel; that which
appears here and there towards its top having been apparently
washed down from the land south of the line.
East of the new line, in a field south of Manor Road at its
junction with Vicarage Lane, appear, in old English letters, the
words "Cing well (site of)." This is, I suppose, the well alluded
to by Mr. Whitaker (Geol. Lond., etc., vol. I., p. 504) when
speaking of the sandy beds in the London-clay which sometimes
give rise to small springs, frequently medicinal—" I have heard
that a spring on the south of Chigwell Row was much appre-
ciated in the neighbourhood."