_Further strictures on the ancient state of this country_, _and on a
wonderful change it appears to have undergone_, _at a very remote and
unknown period_; _from De Serra’s account of a submarine Forest on the
coast of Lincolnshire_.
SOME very remote ages ago, the land, it seems, extended much further out
on the Lincolnshire coast than it does at present; and it appears that
whole forests once existed in places now wholly occupied by the ocean;
which must tend to corroborate what has been already suggested, that the
whole face of the fens was originally a forest. A remarkable Paper,
giving an account of a _Submarine Forest_ on the said coast, appeared in
the Philosophical Transactions for 1799. Part I. written by Joseph
Correa De Serra L.L.D. F.R.S. and A.S. in which the Author informs us of
a report in Lincolnshire, that a large extent of islets of moor, situated
along the coast, and visible only in the lowest ebbs of the year, was
chiefly composed of decayed trees. That report induced him to take a
journey thither for the purpose of inspecting so singular a curiosity.
Those islets, he observes, are marked in _Mitchell’s Chart_ of that coast
by the name of _Clay huts_; and the Village of _Huttoft_, opposite to
which they principally lie, he supposes to have derived its name from
them.
“In the Month of September 1796, (says he) I went to Sutton, on the
coast of Lincolnshire, in the company of the right honourable the
President of the Royal Society, in order to examine their nature and
extent. The 19th of the month being the day after the equinoctial
full moon, when the lowest ebbs were to be expected, we went in a
boat, about half past twelve at noon, and soon set foot on one of the
largest islands then appearing. Its exposed surface was about 30
yards long, and 25 wide when the tide was at the lowest. A great
number of smaller islets were visible around us to the eastward and
southward; and the fishermen whose authority in this point is very
competent, say that similar moors are to be found along the whole
coast from Skegness to Grimsby, particularly off Addlethorpe and
Mablethorpe. The channels dividing the islets were, at the time we
saw them, wide and of various depths; the islets themselves ranging
generally from east to west in their largest dimensions.
“We visited them again in the ebbs of the 20th and 21st.; and though
it did not generally ebb so far as we expected, we could
notwithstanding ascertain that they consisted almost entirely of
roots, trunks, branches, and leaves of trees and shrubs, intermixed
with some leaves of aquatic plants. The remains of some of these
trees were still standing on their roots, while the trunks of the
greater part lay scattered on the ground in every possible direction.
The barks of trees and roots appeared generally as fresh as when they
were growing; in that of the branches particularly, of which a great
quantity was found, even the thin silver membranes of outer skin were
discernible. The timber of all kinds on the contrary, was
decomposed, and soft in the greatest part of the trees: in some,
however, it was firm, especially in the roots. The people of the
country have often found among them very sound pieces of timber, fit
to be employed for several economical purposes. The sorts of wood
which are still distinguishable are, birch, fir, and oak. Other
woods evidently exist in these islets, of some of which we found the
leaves in the soil; but our present knowledge of the comparative
anatomy of timber is not so far advanced as to afford us the means of
pronouncing with confidence respecting their species. In general the
trunks, branches, and roots of the decayed trees were considerably
flattened, which is a phenomenon observed in the _Surtarbrand_, or
fossil wood of Iceland, and which Scheuchzer remarked also in the
fossil wood found in the neighbourhood of the lake Thun in
Switzerland.
“The soil to which the trees are fixed, and in which they grew, is a
soft greasy clay; but for many inches above the surface, the soil is
composed of rotten leaves, scarcely distinguishable to the eye, many
of which may be separated by putting the soil in water and
dexterously and patiently using the Spatula, or blunt knife. By this
method I obtained some imperfect leaves of the _Ilexaquifolium_,
which are now in the Herbarium of the right honourable Sir Joseph
Banks; and some other leaves, though less perfect, seem to belong to
some species of willow. In this stratum of rotten leaves we could
also distinguish some roots of _Arundo Phragmites_.
“These islets, according to the most accurate information, extend at
least twelve miles in length, and about a mile in breadth, opposite
to Sutton shore. The water without them toward the sea, generally
deepens suddenly, so as to form a steep bank. The channels between
the several islets, when the islets are dry, in the lowest ebbs of
the year, are from four to twelve feet deep: their bottoms are clay
or sand, and their direction is generally from east to west.
“A well, dug at Sutton by Joshua Searby, shews that a moor of the
same nature is found under ground in that part of the country, at the
depth of sixteen feet, consequently very nearly on the same level
with that which constitutes the islets. The disposition of the
strata was found to be nearly as follows: clay sixteen feet; moor,
similar to that of the islets, three or four ditto; soft moor, like
the scourings of a ditch bottom, mixed with shells and silt, twenty
feet; marly clay, one foot; chalky rock, from one to two feet; clay,
thirty-one yards; gravel and water; the water has a chalybeate taste.
In order to ascertain the course of this subterraneous stratum of
decayed vegetables, Sir Joseph Banks directed a boring to be made in
the fields belonging to the royal Society in the parish of
Mablethorpe. Moor of a similar nature to that of Searby’s well, and
the islets, was found very nearly on the same level, about four feet
thick, and under a soft clay.
“The whole appearance of the rotten vegetables we observed, perfectly
resembles, according to the remark of Sir Joseph Banks, the moor
which, in Blakeney Fen, and in other parts of the East Fen in
Lincolnshire, is thrown up in the making of banks; barks like those
of the birch-tree being there also abundantly found. The moor
extends over all the Lincolnshire fens, and has been traced as far as
Peterborough, more than sixty miles to the south of Sutton. On the
north side, according to the fishermen, the moory islets extend as
far as Grimsby, situated on the south side of the Humber: and it is a
remarkable circumstance, that in the large tracts of low land which
lie on the south banks of that river, a little above its mouth, there
is a subterraneous stratum of decayed trees and shrubs, exactly like
those we have observed at Sutton; particularly at Axolme isle, a
tract of ten miles in length by five in breadth; and at Hatfield
chace, which comprehends 180,000 acres. Dugdale had long ago made
this observation in the first of these places; and Dela Prime in the
second. The roots are there likewise standing in the places where
they grew: the trunks lie prostrate. The woods are of the same
species as at Sutton. Roots of aquatic plants and reeds are likewise
mixed with them; and they are covered by a stratum of some yards of
soil, the thickness of which, though not ascertained with exactness
by the abovementioned observers, we may easily conceive to correspond
with what covers the stratum of decayed wood at Sutton, by the
circumstances of the roots being (according to Mr. Richardson’s
observations) only visible when the water is low, where a channel was
cut which has left them uncovered.
“Little doubt can be entertained of the moory islets of Sutton being
a part of this extensive and subterraneous stratum, which, by some
inroad of the sea, has there been stripped of its covering of soil.
The identity of the levels; that of the species of trees; the roots
of these affixed in both to the soil where they grew; and above all,
the flattened shape of the trunks, branches, and roots, found in the
islets (which can only be accounted for by the heavy pressure of a
superinduced stratum) are sufficient reasons for this opinion.”