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                      The Geologists' Association.

                                   ON

                       THE RED CHALK OF ENGLAND.

                                   BY

                 THE REV. THOS. WILTSHIRE, M.A. F.G.S.
               PRESIDENT OF THE GEOLOGISTS' ASSOCIATION.

                            A PAPER READ AT

                          THE GENERAL MEETING,

                            4TH APRIL, 1859.

                                LONDON:
                      PRINTED FOR THE ASSOCIATION,
                                  AND
        PUBLISHED AT THE OFFICE OF "THE GEOLOGIST," 154, STRAND.
                                 1859.




LIST OF PLATES.


    PLATE I.

    Fig.
    1. Inoceramus Coquandianus, from Speeton.
    2. Fragment of Inoceramus, striated by glacial action, Muswell Hill.
    3. Nautilus simplex, Hunstanton.
    4. Inoceramus Crispii, Hunstanton.
    5. I. tenuis, Hunstanton.


    PLATE II.

    1. Spongia paradoxica, Hunstanton.
    2. Siphonia pyriformis, Hunstanton.
    3. Cardiaster suborbicularis, Hunstanton.
    4. Ostrea frons, Muswell Hill.
    5. O. vesicularis, Hunstanton.
    6. Exogyra haliotoidea, Hunstanton.
    7. Cytherella ovata, Speeton.
    8. Cristellaria rotulata, Speeton.
    9. Trochocyathus (?) ----, Hunstanton.


    PLATE III.

    1, 1_a._ Vermicularia elongata. Upper and under surface of two
                different specimens, Speeton.
    2. Vermicularia umbonata, Hunstanton.
    3. Serpula irregularis, Hunstanton.
    4. S. antiquata, Hunstanton.
    5. Bourgueticrinus rugosus, Hunstanton.
    6. Diadema tumidum, Hunstanton.
    7. Cidaris Gaultina (?), Hunstanton.


    PLATE IV.

    1. Terebratula biplicata, 1_a._ mag. surface, Hunstanton.
    2. T. semiglobosa, 2_a._ mag. surface, Speeton.
    3. Kingena lima, 3_a._ mag. surface, Hunstanton.
    4. Terebratula capillata, 4_a._ mag. surface, Hunstanton.
    5. Belemnites attenuatus, Hunstanton.
    6. B. Listeri, Speeton.
    7. B. ultimus, Speeton.
    8. B. minimus, Speeton.




ON THE RED CHALK OF ENGLAND

A Paper read 4th April, by Rev. THOMAS WILTSHIRE, M.A., F.G.S.,
Etc., President.


Persons in general take as the type or representative of chalk the
material which mechanics employ for tracing out rough lines and figures.
It is a substance of a bright white colour, somewhat yielding to the
touch, and capable of being very easily abraded or rubbed down.

But the geologist gives a much wider interpretation to the term, not
limiting it by these few characteristics; and, accordingly, he includes
under the same title many strata which would hardly be so grouped
together by the uninitiated.

For instance, there is at the base of the upper portion of the
cretaceous system a certain hard, often pebbly, and highly coloured
band, which, notwithstanding its great departure from the popular type,
is nevertheless styled in geological language the "Red Chalk." This
stratum, the subject of the present paper, nowhere forms a mass of
any great thickness or extent; perhaps if thirty feet be taken as its
maximum of thickness, four feet as its minimum, and one hundred miles
as its utmost extent in length, the truth will be arrived at. It may be
said, also, to be peculiar to England, for the _Scaglia_, or Red Chalk
of the Italians, has little in common with that of our country. The two
differ widely in appearance, in situation, and in fossils.

The first view of the seam in the north is to be obtained about six
miles north-west of Flamborough Head, in Yorkshire, near the village
of Speeton, where its structure, dip, and general appearance can be
remarkably well studied.

Speeton is a small village, a place of no great note in the
business-world, yet of much fame amongst the lovers of geology, inasmuch
as in its neighbourhood there are several interesting formations, to one
of which--the Speeton clay--it gives a name.

In these days of rapid travelling, the village has the great convenience
of a railway-station, from whence the cliffs below can be reached
without the slightest difficulty.

[Illustration: Lign. 1.--Map of Part of Yorkshire, Lincolnshire, and
Norfolk, showing the Outcrop and Range of the Red Chalk.]

As I wish to conduct the members of the Association to the Red Chalk _in
situ_, let us suppose that, starting from some locality near the Hull
and Scarborough Railway, we have taken tickets for Speeton station, and
have in due time arrived at that latter place. On alighting from the
train we must direct our steps to the houses in front, and then inquire
the way to the sea-shore, above which we shall be standing at some
considerable height--say four hundred feet. We shall be told to walk
by the church, to turn to the right along a little lane, and then to
look for an obscure path which passes across the fields. We shall soon
afterwards, being on high ground, be able, by the light of nature, to
find a way down to the sands below.

Whilst descending, let us survey the scene that lies before us. It is a
grand one, rendered picturesque by the broken ground, the solitude, and
the sounding of the waves. Right ahead, there is the open Bay of Filey;
on the left hand, the town of Filey and its Brig; not a ship, as one
might imagine, but a huge mass of rocks of the coralline oolite, jutting
out to sea at right angles from the shore, like a pier formed by human
hands, and crowned on the land-side by strangely cut pinnacles of pink
and rugged drift. On the right hand there are the high and perpendicular
white chalk cliffs of the Flamborough range. As we pass down we shall
meet with a gulley or bed of a small stream, in all probability quite
dry, by following the winding course of which we shall reach the shore.
This gulley passes over an escarpment of diluvial matter (the whole
place being in confusion through the effects of small landslips),
and traverses the Red Chalk itself, the first trace of which will be
rendered visible by means of rolled fragments, which the force of the
stream has at different times detached.

It will be only here and there that we shall find the Red Chalk _in
situ_, because sometimes vegetation, sometimes diluvium, sometimes
fallen masses, entirely conceal its real position. However, there will
be plenty of rounded pieces at the feet. Some of these had better be
examined on the spot, in order that we may gain a clear perception of
the appearance of the bed, should we meet with it again. These pieces
are found to be hard and rough to the touch, and of a bright red tinge,
though occasionally marked with streaks of white. Most likely on some
of their sides a fossil or two will be seen peeping out; a blow from a
hammer will divulge still more. So plentiful are the rolled fragments,
that a few hours' work will satisfy the conscience, and fill the pockets
of the traveller.

If I might be permitted to give advice to any member of our Association
who should hereafter visit the place, it would be this--that it would
be well for him to carry away moderate sized boulders entire, rather
than to break them on the spot. The fossils will best be developed at
leisure. The material is so hard, and the fossils so brittle (especially
the belemnites and serpulae), that imperfect specimens only will result
from the quick and rough treatment of the hammer. The "find" will not
produce any very great variety, only numbers; terebratulae, serpulae, and
belemnites will be all that will be obtained.

Having now procured specimens, we had better walk southward along the
shore; after a short time will be seen a fine perpendicular section of
this particular stratum; we shall notice it is bounded on the one side
by the White Chalk, to which it is parallel; on the other by the Speeton
clay, which is not conformable to it, that is, not parallel.

The thickness of the bed of the Red Chalk is at this place, as I said
just now, about thirty feet. First of all, taking it in descending
order, that is to say, having reached its limit at the White Chalk, and
retracing our steps in the direction of Filey, we notice about twelve
feet of red matter containing serpulae, and we note that the upper
portion of this division is much filled with greyish nodules, showing
that the change from the White Chalk to the Red is gradual. Next comes
a bed of about seven feet thick, of darkish White Chalk; and finally,
another bed of about twelve feet thick, of bright Red Chalk, containing
belemnites and terebratulae. The whole is followed by the Speeton clay,
of which a short and accurate account will be found in No. 13 of THE
GEOLOGIST magazine. The line of division between these two being
well marked by runs of water, which are caused by the percolation
through the chalk being stopped by the impervious clay.

The Speeton clay is singular in some of its characteristics. At its
upper portion, in contact with the Red Chalk, it contains fossils
belonging to the Neocomian or Greensand era, whilst at the lower part
there are the representatives of the Kimmeridge clay. And thus it would
appear to be one of those peculiar formations which have resulted from
a number of beds thinning out, and becoming absorbed into each other.
Three of the well-marked fossils of the Speeton clay may be adduced:
_Belemnites jaculum_; a small crustacean, _Astacus ornatus_; and a large
hamite, called _Hamites Beanii_.

To the south of the Red Chalk at Speeton, and adjoining it, occurs,
as I lately mentioned, the White Chalk. The fossils in this part are
not numerous; an inoceramus, a terebratula, and rarely an ammonite,
are found. But the White Chalk higher up, that is, farther south,
below Flamborough Head, near Bridlington Quay, is very fossiliferous,
containing corals, echini, a bed of marsupites, as well as that very
remarkable and extensive collection of marine forms, the silicified
sponges, thousands of which can be seen at low water scattered up and
down, and imbedded in the scars, or rocks. This chalk, however, has its
drawbacks, for being very hard--indeed, so much so as to ring under the
strokes of a hammer--specimens cannot be obtained without much trouble.
I must make an exception with regard to the sponges. They are composed
of silex; hence, long soaking in very dilute hydrochloric acid will do
more and better work after the fossils have been brought home, than
fifty chisels. The calcareous matter is slowly dissolved away, and then
forms come into view as delicate and lovely as any that can be noted in
the modern sponge tribe. Most of the common kinds of the Flamborough
sponges will be found figured and named in Professor Phillips' Geology
of Yorkshire; the rarer in the Magazine of Natural History for 1839.

Let us now return to the village of Speeton, and endeavour to follow the
winding course of the Red Chalk to its visible termination, some hundred
miles to the south-east, in the county of Norfolk.

By a reference to the map (page 