The Dorset County Express and Agricultural Gazette.
Dorchester, Dorset, England, 1867-01-01 00:00:00

ISLE OF PURBECK.

KlMltaltlDoll CLAY. —Kimmeridge clay geti the
name from Kioinieridge, the:place in tbellsle of Purbeck
where the beds of the shale are sees in the cliffs of the
(cast, and also on the coast of the Isle of Portland. On
the coast of Little Knimmidge the cliffs are abrupt,
and composed of a slate clay of • greyish yellow colour,
finely slaty, *penile*, both animal and vegetable
remains. The plates of whisk the rook is composed
become muds more evident after it has undergone some
decay, or, wine sound, after it bas been exposed to the
are. It divides spontaneously into tubular mason
The fracture of the rock is earthy, with very mad
specks or nodules of indented clay. The outside of the
rock is covered by • thin layer of calcareous spar. The
mess efferveseeo with acids, but*, nodules of indented
clay do not. This rook lades gradually into a bite's,.
Mona shale; but the first transition is into • state clay
a lighter or darker colour, the joints of which
de covered with iron pyrites. It bu roe with
a yellowish flame, giving out • sulphurous 1.1111111,
end becomes afterwards of • light gray colour.
The second transition is to • bituminous shale
called " stoney oral" (Kimmeridge clay), the
.Ip,ific gravity of whioh is 1.319. Its colour is dark
brown, without any lustre; it effervesces slightly with
sciat, contains no iron pyrites, and burns with a
yellowish, rather smoky, and heavy game. The smell
is bituminous, but not sulphurous Th. Kiennteridge
coal rests upon and is covered by the slate clay first
described. The beds of blue slaty or greyish day con-
tain selonite and layer' of highly bituminous shale,
which are used as fuel, .I,d hellos the name of Kimme-
ridge cool, which is applied to the whole formation, in.
chiding the clay. It has been erroneously suppowd
that thine beds were the NM* with the alum:low.
shale of Whitby in Yorkshire, which belongs to the
lira beds. These beds contain the selenites of Oxford.
shire, which are daily formed by the adios of dawn-
Posing pyrites upon the oyster shells and other fords
contained in them. Alum was formerly manufactured
In the parish of Kimmeridge. The organic Teresina are
&idly of extinct gener• of leeerten, evidently calculated
for • marine abode. The qesdropedal species differ
from thew of the lima, and bones apparently of the
cedarma likewise occur, and also of the enttle-fish. The
shells are nunierone—univalve chambered and not
.chambered, and many bivalve. The positious of the
Aimmeridge day are overlooked by the rooks of the
upper oolite formation which has the most commanding
.appearance in Portland Isle, in the Vale of Peaniey,
at Swindon, Pad in the Vale of Aylesbury. The
clay oeempies • tract in Wiltshire, rarely emoting
two miles in breadth, but exteeding in length from the
Berkshire border to the west of Devises, beyond which
it is covered by the westward extension of the overlyinr
formation.. At Swindon bs de ef oolitic freestone divide
beds of clay the% are not well delleeid, and probably it is
the Kimnieridge bed that occupies the Vale of Wardoor,
and extends into Dorestabire, where the formation runs
in • narrow vale. In the counties of Berke and Becks
the Kimmeridge slay is seen in the few appearances of
the upper oolite formation, and is often wanting the
.oloncla supporting the Portland beds. In Lineohishir
it pwes beneath the Wolos, sad oessoise the north
side of the Vale of Pickering in Yorkshire. where it
passes into the Semeton clay shove. The Kimnieridge
clay forms the substratum of the whole 1-1 e of Portland,
and rises high on its northern face, where it is capped
by an abrupt esearpment of the superior colitis beds
All the strata sensibly decline, though not under a very
rapid angle, to the south, bringing the line of junction
between the clay and oolite to the level of the sea. All
the coasts of the island are deep, the bass of Kin,
meridge slay forming • sloping talus. surmounted by
wage of the *elite, warred by numerous quarries. In the
Isle of Purbeck a depth of 700 feet has been a.signed to
the Klonestridge clay but it seems excessive. Dr. Busk.
land states SOO. Near Oxford, where the beds thin off,
the thickness cannot exceed 100 feet. In the pit,
at Lateingwell, pear Bagley Weed, it was only 70 feet,
as use doer Mined from boring for omit In the Vale of
White Hone and at Swindoe it was penetrated lora well
to the depth of 233 feet, and the additional thickness of
the incumbent beds on the bill, being takin at only 70
feet, the stratum will appear 300 feet thick. In Lincoln-
shire and in Yorkshire its thickens generally appears
much less, through the oncomforinity of the chalk
strata. The water in this formation is deficient, and of
bad quality, and from its retentive nature it must
generally he piertodithrough'before'asecopions supply
can be found. The Kimmeridge clay Is nearly hon.
metal, dipping in an almost ineripmei.ble angle south'
south-east. Immediately on the south of Abingdon the
clay pursues its course weewards through the Vale of
Berkshiee, following the line of the Wilt. and Berk.
Canal as far as Wootton Bassett, where it tams mare to
the south, sad ranges on the eased fldne and of emend,
reposing all the any on the loser edge of the coral req.
Near the latter place the chalk and subjacent green sand
°wadisi and conceal .advancir4 in a sort of projecting
cape even into the district of the great °elite. In the
above interest of country. the Portland bed of stone
may men appears mends, on the day, being concealed
by the alone' detea, or overlaid and hidden
by the superior strata. The typical character
of the Kinoneridge clay is • blue slaty substance,
with .6120" sometimes highly bituminous, being
a thick clay deposit forming a odd stiff soil
In broad valve?, and without wirings. The quality
or the surface ground is inferior both to the clench and
lias clays • either for arable purposes, and in pastorate
the Iterbnge teede to sourness, and the texture is very
clammy and repulsive to the tender growth of einem.
The summer fallowing of the land is imperatively
necessary, as the root crops are completely excluded, "ad
the land requires en ample manuring of term yard along
with dung to lay the foundation of the following coops.
Three two substances are the only articles which the
soil allows to act upon it as fertilisers. Though bean.
may be used as an eadaional crop, and probably with
advantsmi, yet it dodo not bold • creditable position in
the rotenone of croppings on Kimmeridge clays. The
plaid ?squires • 111.100041 losininese of the goal in which
It grows midi advantage, and the eerie degree of
of loamy adhesiveness is not often found, and most cep.
teinly does not exist in the formation of day that is
now under consideration. Unless the quality of the
BA freely admit some preparation of land in the spring
end the drilling and complete bone and hand-hoeing of
the beans, the crop is much hotter omitted; for the
plant in broadcast
abundance of weeds, which, being perfected in the seeds
by the late harvesting of the beans, add • profusion
of the germs of future vegetation, to PerPlitz anJ
encumber the clearing of the ground. On the inferior
day leads of any denomination beams are better omitted
and the gracing fashioa adopted, thus : First year,
fallow (dung and lime, In 150 wails); monad year,
wheat; third year, slaver; fourth year, posture; Mb
veer, dill,; sixth year, ode. In the case of hems
being used: First yew, fellow; emceed year, whenk;
third your clover; foie* year, pesters; fifth
year, betas; sixth year, wheat or seta. Barley might
be used on the suronser-fallow of the land, and will
succeed, with good working of the lied, ample manariag,
and • dose of lime in the dlowanes of 150 bushels to an
sere. Pest is inadmissible; but vdehei, both in the
winter and spline varieties, may be used thus: First
year, fallow; wood year, wheat; third year, clover;
fourth year, oats: Afth year, eddies; lath reet,
wheat. or—fourth year, pasture; Mk year. setae. ;
sixth year, oats; seinterk year, beans' slabs year,
wheat. The fret rotation, on the pastariag whams, is
deakiedly the most preferable: sad the sitossaary
MIMI are speeded below • limplusik ha5...1.64;
enelsoleet. a qmarlor et • bushel; =ado+ (omens, 4164.;
411 a.; dftedail, fibs; band fescue, Mo.; field
hrosse, 21ha.; redelover, 31ha.: whits slower, 4lles per
acre. The draining of the Kimmeridge days reclaims •
frequency el Ilve or an yards is the position el the
drama, sad dem depth and Nl* wish paierislo on
Wore deourand.—Mark Low arm.