Clay pit

“ Here the shelly beds of the Plastic clay have been found in digging wells at the depth of thirty feet. At New Cross, near this point, they are found at the surface.
4. The pits at Loam Pit hill, described at page 285 of this paper: a section of these pits is represented in this Plate, No. 2.
5. Pits of sand and chalk on Blackheath hill.
6. The cavern beneath the point at Blackheath. This is an extensive adit driven into the substratum of chalk.
7. Sand pits in the middle of Blackheath; these are situated in the upper sands of the plastic clay formation. ”

“ In a pit called Jordan’s pond, in an abandoned brickyard on the east of the road to Stixwould, it is at least 16ft. thick; also, in a large pit in Kirkstead, near Hogwood, some half-mile south-east of the Abbey Inn, which was dug to procure this clay, for “claying” the light super-soil, otherwise almost barren, it is many feet thick. Ammonites and other fossils are plentiful in it, often cemented together with veins of gypsum. Both these pits are mentioned in the Government Geological Survey (pp. 152, 153) of “The country around Lincoln.” ”

“ The slate clay at Mary Ann Pit contains impressions of aquatic plants, vegetable impressions similar to those of the Derbyshire collieries have also been observed in the Ballycastle district.
Clay ironstone occurs both in nodules and beds, and brown spar passing into sparry iron ore has been observed at the coal works of Ballycastle, where it forms a bed of some thickness traversing the cliff at a little depth below the principal seam of coal. ”

“ In clay that has never been dried, as for instance, that found under wet meadows from which the water has but recently been drawn, we should not, of course, expect to find these cracks. Accordingly, we find sometimes in clay pits, excavated below the permanent water-line, and in wells, that the clay is in a compact mass, and tears apart without exhibiting anything like these divisions. ”

“ In the very centre of the principal street, which appears to have once upon a time been level, are three or four immense clay-pits, serving as a receptacle for dead dogs, cats, bones, vegetable refuse, and, in a word, every description of rubbish and nuisance a very dirty population can convey to or discharge in them. ”

“ On the inner edge of this platform at the Plumsted Common brick kilns, which are at the base of the north-east extremity of Shooter's Hill, a large section exposes the London clay, abounding in selenites and septaria. This clay is dug for brick tiles and coarse pottery. In the same field with the clay pits and on the north side of them a shaft is sunk 120 feet to the surface of the subjacent chalk, which has been extracted to the further depth of 24 feet, being the object for which the shaft is made. ”

“ It contains organic remains in very few places. Is it not improbable that this bed is contemporaneous with some of the upper strata of the plastic clay formation which we find at Loam Pit Hill, at Blackheath, and in the Isle of Wight, at which last place the beds belonging to this series are accumulated to a thickness far greater than has been yet noticed in any other spot, amounting at Alum Bay, according to Mr. ”

“ Hard refractory clays often remain porous and are a fruitful source of crazing and breaking. The addition of flint or fine washed sand, finely powdered grog, or pitchers, or even refractory China clays, in quantities varying from about 5 per cent to 20 per cent, but settled only by repeated trials, will stiffen up or open out rich clays inclined to warp or burst. Rich fusible clays added to hard clays may stop the crazing, or the fusing point may be lowered by the addition of spar. Stiff gravelly clay will require finer sieving or repeated washing to rid it of some of the grit or sand. ”

“ In composition, ball clays appear to consist chiefly of a hydro-alumino-silicate corresponding to the formula H4Al2Si2O9, and in this they very closely resemble the china clays (kaolins) . The latter are, however, but slightly plastic whilst the ball clays are [65] amongst the most plastic clays known. The china clays are also much more refractory than the ball clays owing to the somewhat larger proportion of alkalies in the latter.
Pipe clays are an inferior quality of ball clay; they contain rather more iron and alkalies and considerably more silica. ”

“ Along this line, especially in the vicinity of Hill lake, there is a zone of deep clays of very promising agricultural value. In the area of granite farther north, the whole future, so far as agriculture or forestry is concerned, depends upon the general depth of the boulder clay. From the mere fact that it is a drift deposit, this depth constantly varies, but only a detailed soil survey of each township could show where and how much. There are large areas of almost pure rock outcrop and muskeg of little or no value even for timber production. ”

“ None the less, clays are notably impure, and in many there is a large admixture of quartz sand. The kaolin, derived originally from the decay of other silicates, is rarely freed from a variety of minerals and rock-fragments that were associated with it in its place of origin. Grains of quartz and unaltered felspar a tenth of a millimetre in diameter distinctly "lighten" a clay soil, on account of their relative coarseness. A sandy clay is styled a Loam, and a fine-grained loam furnishes the ideal soil for the general purposes of a farmer. ”

“ Agriculturally, the Lias clays are laid down for grass, but the lighter soils are useful for arable purposes.
The 'Oolitic clays,' which are also Jurassic, usually contain limestone in the form of nodules, but are nevertheless important. They form a broad belt above the Lias from Dorset to Yorkshire, and include the blue clays of the Purbeck beds, stiff blue bituminous Kimeridge clays, the irregular, sandy Coral Rag clays, the famous Oxford clay (from which the Peterborough and Fletton bricks are made) , the Kellaways blue clay, and the Fuller's Earth deposits. ”

“ And at once the heavy gloom that had hung over the explorers became expelled, and we all got under the shadow of the bridge and messed about with clay.
"It will be jolly!" Alice said, "and we can give the huge platters to poor cottagers who are short of the usual sorts of crockery. That would really be a very golden deed."
It is harder than you would think when you read about it, to make huge platters with clay. It flops about as soon as you get it any size, unless you keep it much too thick, and then when you turn up the edges they crack. ”

“ Glacially deposited clays are characterised by their heterogeneous composition, some of them containing far more sand than true clay, whilst yet retaining a sufficient amount of plasticity to enable them to be used for rendering embankments impervious and for the manufacture of common bricks, and, occasionally, of coarse pottery; others contain so much sand as to be useless for these purposes. Most glacial deposits contain a considerable proportion of stones and gravel which must be removed before the clay can be used. ”

“ Clay-pans usually occur in the neighbourhood of salt lakes, and are merely shallow depressions with smooth clay bottoms. Though as a rule not more than a few inches to a foot in depth, I have seen them in places holding four to five feet of water. Immediately after rain all clay-pans are fresh, before long some will turn salt; those containing drinkable water are often distinguishable by the growth of cane grass which covers the bed, a coarse, rush-like grass of no value as food for stock. ”

“ When clay-hills have veins, water may accumulate in them and flow, and if very dark yellow clay overlies light yellow calcareous clay, which may rest upon hard blue clay, it is obvious each stratum is somewhat differently affected by weather and air, and therefore movement is to be expected. The edges of clay-hills are always likely to slip, especially should they be in the form of spurs. ”

“ If the transporting stream flows through valleys whose sides are formed of limestone, chalk, sandstone or other materials, these will become mixed with the clay, and to so great an extent has the mixing occurred that very few clays occur in a state even approximating to purity. The majority of clays are contaminated with iron oxide, lime compounds and free silica in such a fine state of division that it is impossible to purify them completely without [50] destroying the nature of the clay. ”

“ Although clays occur in deposits of almost all geological periods, many of them are of little or no commercial value. This may be due to their situation or to their composition and other characteristics. Thus, a Coal Measure clay is ordinarily quite inaccessible, and to sink a shaft specially to obtain it may be an unprofitable undertaking; if, however, a shaft is sunk for coal the clays in the neighbourhood of the coal seams are rendered accessible and, usually, a certain amount of such clays is brought to the surface in order to remove it out of the way of the coal miners. ”

“ The next deposit, supposing these patches of sand and gravel to be of one age—a very doubtful matter,—is the Boulder Clay—a stiff, tenacious clay, often studded with pieces of chalk, from minute grains to biggish lumps, which commonly are fairly well rounded, together with flints, both rounded and angular, and fragments of other rocks. ”

“ By careful washing, most boulder clays may be purified sufficiently to enable coarse brown pottery to be made from them. Clean deposits of sufficient size to be worked without any purification are occasionally found. [67] Usually, however, the boulder clay formation is somewhat treacherous as it is difficult to ascertain its nature; boreholes are apt to be quite misleading as the formation is so irregular in character. ”

“ The clay or brick-earth is of a reddish hue, and rests upon a chalky Boulder Clay, which is exposed farther up the hill. It ranges in thickness from about 4 to 6 feet; and above it are sands and gravel, the latter varying in thickness from about 2 to 6 feet, and of much the same character as that of the Warren Hill pits, but containing far less chalk. The sand occasionally comes down in pipes or pockets into the clay, and some of the worked flints occur in it, as well as in the clay. ”

“ E. H. L. Schwarz (35) has suggested that many clays are composed of small globular masses of plates so arranged as to form an open network (fig. 4) which is sufficiently strong not to be destroyed by pressure. In the presence of water and much rubbing the plates are separated and are made to lie flat on each other, thereby giving a plastic and impermeable mass. If this is really the case it would explain the porosity and large surface of some clays and might account for their adsorptive power.
Fig. 4. Illustrating the structure of a 'clay crumb.' (After Schwarz.) ”

“ From the higher parts of the road, and from the rocky pass which overhangs the river, there is an extensive view over the barren sandy waste on the north bank of the river. The lacustrine clay is, at this end of the valley, very thick and but little excavated, forming cliffs which rise close to the river, which has, as it were, worn for itself a narrow channel in the clay formation. The banks or cliffs are of very different heights, and many of them consist of alluvial gravel and boulders, overlying and quite obscuring the clays. ”

“ Their colour is dark blue or grey and they are usually stiff or somewhat shaly in texture with layers of variable composition. The closely associated Cornbrash (limestone) is a source of trouble unless great care is taken in the selection of the material. 'Oxford clays' are not infrequently traversed by seams of poor coal or by oil-shales.
Agriculturally, Oxford clay is difficult to work and, while much of it is valuable, large portions are poor and cold. When well exposed to frost it is made much lighter, but even then is not very suitable for wheat and autumn sown crops. ”

“ For many industrial purposes, particularly for the manufacture of refractory goods, the clays and shales of the Carboniferous System are highly important. The less valuable burn to a reddish colour, often spoiled with many grey spots of ferrous silicate derived from the pyrites in the clay, but the purer varieties burn to a delicate primrose or pale buff tint and are amongst the most heat-resisting materials known. The Coal Measure clays of Yorkshire are particularly esteemed for their refractory properties ”

“ Erotion and Rhanto laughed at the recollection.
"I smashed the figure to pieces," said the boy. "I broke the clay into fragments, and I have decided to touch no other than that in the pottery—when I make up my mind to return there."
He flung his arms around the shepherdess and rested his head upon her shoulder, rubbing his cheek against her neck with an almost feline caress.
"Why should I work?" he added. "I spent many days kneeling before that accursed clay, struggling to make it take on the form of her body; but it is useless. Clay is clay, and it cannot become living substance. ”

“ Some folk appear to believe that if they only sit under a pulpit in the morning, they have earned a dispensation for the rest of the day. [Pg 57]
The cliffs now are sixty feet in height, broken by frequent slips in the upper stratum of clay, and numerous cracks running along the path marks the limits of future falls. One of the slips appeared to be but a few hours old, and the lumps, of all dimensions, with patches of grass and weeds sticking out here and there, lying in a great confused slope, suggested the idea of an avalanche of clay. ”