at "Oakhill Quarry," Epping Forest. 233
shall have faults on the western side of each. There is no
doubt that the western slopes have the same character with
each other, in both cases being considerably steeper than the
eastern ones.2 Until the dip of the beds has been more
accurately ascertained, fig. 1 will give an approximately
correct idea of the strata in this part of Essex. The section
is constructed from those given in vol. iv. of the 'Memoirs of
the Geological Survey,' where sections are described at
Hainault Forest, Loughton, Waltham, and Waltham Cross;
and particularly from the section of a well dug a few years
since at Loughton by the Great Eastern Railway Company,
for the particulars of which I am indebted to Mr. Langley,
Engineer to the Company, who has kindly furnished me with
the same. Unfortunately, I learn from him that no fossils
were obtained when digging this well, the only one, I believe,
in this part of Essex which passed through the Chalk. The
section is given in the diagram (fig. 1), and is as follows :—
The upper beds of the clay pass by almost imperceptible
gradations from clay to sand into the Bagshot Sand, which
is succeeded by the Bagshot Pebble-bed, consisting of flint
pebbles. These beds, although once covering the whole area,
are now only to be seen in sundry outliers at Brentwood,
Havering, Theydon Mount, Oakhill, and High Beach. From
the present slopes and valley-bottoms they have long since
been denuded away. The principal difficulty about these
beds, and that is rather a serious one, is to distinguish
between the pebble-bed of the Bagshot and the later glacial
gravels, or gravels of denudation, which are to a large extent
composed of the re-sorted materials of the Bagshot Pebble-
bed. These beds may be distinguished by their pebbles—the
Bagshot Pebble-bed consists entirely of flint pebbles well
2 I venture to throw out the suggestion that the greater steepness of the
western slopes may be attributed, not to the faults, but to the greater
denudation to which hills having that aspect have been exposed from the
prevailing westerly and south-westerly winds and rain, which may have
had considerable influence upon strata of such a character as the London
Clay.
R