THE GENERAL FEATURE OF THE CLIFFS CONSIDERED—CAUSES OF IRREGULARITY, AND
THE GEOLOGICAL STRATA COMPOSING THEM.
THE cliffs {55} extending from Hasborough to or a little beyond Cromer,
are found, upon approaching near, to be extremely irregular. In some
places small promontories or points project, in others small bays are
formed, according to the influence of the sea, and the materials
composing their structure. Their perpendicularity is partially averted
from the fallen masses deposited at their base; which, where the cliffs
are lofty, are often considerable; arising either from the sand or clay
beneath the more solid strata being removed; or the landslips which
ensue, from fresh water springs abounding in certain localities. Thus,
in the winter of 1825, a fallen mass was precipitated from near the
light-house at Cromer, which covered twelve acres, extending far into the
sea, the cliffs being two hundred and fifty feet in height; and Mr. Lyell
observes, the undermining by springs has caused large portions of the
upper part of the cliffs, with houses still standing upon them, to give
way, so that it is impossible, by erecting breakwaters at the base of the
cliffs, permanently to ward off the danger.
The wasting of the cliffs is also accelerated from other causes—the
continuation of strong north-easterly winds, of drought producing
fissures from their superior surface downwards, heavy rains, and after
severe and successive frosts.
The cliffs generally consist of clay, sand, and loam. By some writers
they have been termed mud cliffs, from their dark colour and general
appearance. Mr. Lyell includes them in a series called the Boulder
formation.
Mr. Woodward, in his Outline of the Geology of Norfolk, considers them to
be of diluvial origin; but upon close inspection, they are found to
contain strata and fossils which partake of the characters and may be
ascribed to various parts of the tertiary period.
The cliffs form part of an extensive series, extending from Hasborough
Lighthouses to Weybourne, north-west of Cromer, comprising a distance of
about twenty miles, and are supposed continuously to rest upon chalk.
In some places the cliffs are very regularly stratified, presenting at
various parts, layers of red and white sand, but in other places they are
wholly devoid of stratification, exhibiting one continuous mass of till.
This position of the various strata will be found pretty correct:—
Tertiary
Diluvial 1 Brown clay: containing bones of the horse, ox,
&c.
2 Till
Newer Pliocene 3 Crag
4 Fresh water, lacustrine, lignite, &c.
Older Pliocene 5 Blue clay containing bones of
elephants, rhinoceros,
6 Red gravel &c.
Eocene 7 Green sand: with bones of extinct mammalia.
8 Chalk
The entire series of these cliffs bears evidence of great and successive
changes; the strata, in many places, are folded and bent, and
superimposed upon others, which have undergone no dislocation whatever.
On the till, with an even horizontal surface, beds of laminated clay and
sand are seen to repose, succeeded by vertical, bent, and contorted beds,
having a covering of coarse gravel and flints.
Between Bacton and Mundsley, small pits or furrows may be seen at various
distances, from the top of the cliffs filled with fragments of white
chalk; regular strata being superimposed. Many of these furrows are
several feet in width and depth. In the till, to the east of Bacton,
these furrows are again largely developed.
The till and marl, layers of which are met with towards Mundsley,
frequently present grooved surfaces, and at different places appear to
dip into the beach, the grooves left being filled with superimposed sand.
The gravel also takes a like dip.
While on the one hand there are evidences which prove the slow deposition
of some of these strata, on the other there are proofs of great
convulsions and derangement.
As a regular description of the separate strata may not prove
uninteresting, let us inquire into the first—
TILL.
This term is a provincial word, widely used in Scotland for similar
masses of unstratified matter, which contain boulders; and the same term
has been applied by Mr. Lyell to this part of the Norfolk strata.
The till is of a dark blue colour, somewhat resembling that of the London
clay, and has been classed by some writers with that formation, because
of the boulders with which it abounds. Mr. Woodward calls it blue clay.
A positive distinction between this and the regular blue clay, however,
must be made.
This till forms a large portion of the cliffs between Hasborough and
Mundsley, rising in some places from twenty to nearly eighty feet in
perpendicular height.—The whole of its organic remains appears to have
been washed from other formations, to be deposited in it, and it
contains, mingled with them, fragments of almost every rock of the
secondary and primary series; comprehending immense blocks of granite,
porphry, greenstone, oolite, lias, chalk, pebbles, trap, micaceous chist,
sand-stones of various kinds, chert, marl, &c. Near Hasborough it is
much intermingled with chalk.
The second stratum, as we descend beneath the till, is the
CRAG.
A layer of which, between the watch-house and coal gaps at Bacton, has
been termed by Mr. Lyell hard ferruginous crag. It consists of several
thin plates, containing compressed wood, fragmentary and whole shells,
intermixed with clay, gravel, and white sand. This bed forms a dip
towards the north-west, having a support of red sand on the one side, and
green sand on the other. A section of the crag is more largely developed
at Cromer, Runton, and Weybourne. Between Bacton coal gap and Mundsley,
vertical layers of crag occur, composed of thickly cemented fragments of
shells.
Immediately beneath the crag occur those formations which are generally
termed Fresh Water, consisting of lignite and lacustrine deposits.
LACUSTRINE.
At several spots between Hasborough and Mundsley, these deposits may be
examined. They contain many species of shells, with fish and bones of
mammalia.
The first of these occurs at a place called Ostend, between Hasborough
and Bacton, about half a mile from the latter place. It is composed of
bluish mud, with occasional patches of brown clay, and extends several
yards along the beach. This formation was discovered by Mr. Green, in
August, 1841.
About two hundred yards from the forest peat at Bacton, the second
lacustrine bed occurs. It is confined to occasional patches about the
middle of the cliff, near the watch-house gap. The shells are deposited
in thin layers of sand and blue clay, containing much wood, which appears
as if bored by some insect.
The third lacustrine formation is at the village of Mundsley, and is
distinguished from the other cliffs by its dark muddy appearance. Its
height is about twenty feet, and it extends one hundred yards along the
beach.
Mr. Lyell, referring to this bed, says, “It consists of brown, black, and
grey sand, and loam mixed with vegetable matter, sometimes almost passing
into a kind of peaty earth, containing much pyrites.”
LIGNITE.
This name has been given to extensive forest beds, containing much
carbonized wood.
The deposit prevails very generally along the Norfolk coast, and may be
instructively examined at Hasborough, Bacton, Mundsley, Trimingham, and
Cromer.
At Bacton extensive sections are laid bare after high tides. They are
mostly formed of black peaty earth, which may be separated into thin
layers, and has generally an aluminous taste, and abounds with pyrites.
At Bacton the depth of these sections, from the top of the cliff, is
about five feet; at Ostend, between Bacton and Hasborough, about thirty,
and at Mundsley, one hundred feet.
These deposits are occasionally mixed with masses of red sand, containing
pipes of hard clay.
This formation presents the appearance of a wood, having been overthrown
and crushed in situ; for after strong north-west winds, the stumps of the
trees may be seen really standing, with their strong roots extended, and
intermingling with each other. In the winter of 1840–41, Mr. Green
measured some of these trunks, which were then exposed about a foot from
the root.—One measured five feet eleven inches round, and the other five
feet.
Whilst at Bacton this bed is formed of black peaty earth, at Ostend it is
mixed with a greenish sand. Mr. Lyell speaks of that at Hasborough as
“laminated blue clay, about one foot and a half in thickness, part of the
clay being bituminous, and inclosing compressed branches and leaves of
trees.”
Mr. R. C. Taylor, in his Geology of Eastern Norfolk, observes of the
deposit generally:—“It consists of forest peat, containing fir cones and
fragments of bones; in others of woody clay; and elsewhere, of large
stools of trees, standing thickly together, the stems appearing to have
been broken off about eighteen inches from the base.”
The Rev. James Layton, cited by Mr. Fairholme in his Geology, states, in
a letter, “the line of crushed wood, leaves, grass, &c., frequently
forming a bed of peat, extends just above low water mark. About this
stratum, numerous remains of mammalia are found, the horns and bones of
at least four kinds of deer, the horse, the ox, hippopotamus, rhinoceros,
and elephant. These fossil remains are found at Hasborough and its
neighbourhood, on the denuded clay shore. At Mundsley, they are found in
the cliff. This stratum may be seen as the underlying formation, along
the whole line of beach from Eccles to Mundsley.”
At Cromer, Mr. Simons has observed, beneath the drift, several feet below
high water mark, a bed of lignite, in which were found the seeds of
plants, &c. He also observed ten or more trees, in the space of half an
acre, exposed below the cliffs eastward of that town, the stumps being a
few inches, all less than a foot, in vertical height, some no less than
nine or ten feet in girth, the roots spreading from them on all sides,
throughout a space of twenty feet in diameter.
Mr. Richard Taylor believes this bed, as visible at Hasborough, to be an
extension of the well-known stratum at Watton cliff and Harwich. “There
is,” he says, “evidence sufficient to prove that it extends more south
than Palling, even as low down as Winterton, and Caister; also at
Lowestoft.”
The two last strata nearest the chalk are the
BLUE CLAY AND THE RED GRAVEL.
These two beds “seem to have been deposited contemporaneously, as they
are much intermixed, and every where contain the same species of
mammalian remains. From the unusual quantity of bones contained in these
strata, they have been provincially termed the Bone Rocks, but from the
immense quantity of elephants’ bones annually exhumed, they may, for the
sake of distinction, be termed the Elephant Beds.” In some places the
blue clay is deposited upon the red gravel.
The red gravel appears to be composed of rolled materials, which no doubt
have been brought to this place from some distance. It comprehends a
mixture of red sand and gravel, ferruginous and ochraceous nodules; blue
clay, peat, sulphur, loam, flints, pebbles, masses of granite, porphry,
fragments of and whole bones, and is much mineralized by iron.
These rocks are traceable to a considerable distance beyond Cromer.
The immediate bed upon which the strata rests appears to be
CHALK.
This is met with about half a mile north-west of Mundsley, about low
water mark, and for upwards of a mile forms the beach. Near Trimingham
three very remarkable protuberances, which rise up and form a part of
lofty cliffs. Further northward, masses of chalk are included in the
drift, or crop out in the interior, at a short distance from the shore,
as at Overstrand, near Cromer, where a pit has been worked, in which the
chalk is in a very disturbed and shattered state. At Cromer, the chalk
has been again detected, and is every where the fundamental rock, lying
about the level of low water, and rising on the north of that town, to
the height of some yards above the level. At Sherringham it ascends
above high water mark, and enters largely, from thence to Weybourne, into
the strata of the cliffs.
From the appearance then of so much chalk in the immediate neighbourhood,
and some of it apparently in an undisturbed state, as may be seen by its
horizontal layers of flint at Sherringham, beyond doubt its existence may
be concluded both to the east as well as the north.
In the year 1836, the humerus bone probably of the Great Mastodon, was
found at Bacton, after a very high tide, one side of which, from the
appearance it presents, must have reposed upon chalk. This bone was
discovered in the red gravel, which, in many places, is the nearest bed
to the chalk. Fragments of chalk are attached to the bone.
In the early part of this year the tibia probably of the same animal, was
exposed, and obtained after a high tide by Mr. Green, in whose possession
it still remains.