The bone-bed of Axmouth in Devonshire and Westbury and Aust in Gloucestershire, in the Penarth or Rhaetic series of strata, contains the scales, teeth and bones of saurians and fishes, together with abundance of coprolites; but neither there nor at Lyme Regis is there a sufficient quantity of phosphatic material to render the working of it for agricultural purposes remunerative.
The term coprolites has been made to include all kinds of phosphatic nodules employed as manures, such, for example, as those obtained from the Coralline and the Red Crag of Suffolk.
Thick, containing rolled fossil bones, cetacean and fish teeth, and shells of the Crag period, with nodules or pebbles of phosphatic matter derived from the London Clay, and often investing fossils from that formation.
"The nodules, having been imbued with phosphatic matter from their matrix in the London Clay, were dislodged," says Buckland, "by the waters of the seas of the first period, and accumulated by myriads at the bottom of those shallow seas where is now the coast of Suffolk.
The phosphatic nodules occurring throughout the Red Crag of Suffolk are regarded as derived from the Coralline Crag.
An acre used to yield on an average 300 tons of phosphatic nodules, value £750.
The Chloritic Marl in the Wealden district furnishes much phosphatic material, which has been extensively worked at Froyle.
Phosphatic nodules occur also in the Chloritic Marl of the Isle of Wight and Dorsetshire, and at Wroughton, near Swindon.
In 1864 two phosphatic deposits, a limestone 3 ft.
Phosphatic beds, supposed to have had a coprolitic origin, are found in the Lower Silurian rocks of Canada.
Teall, On the Potton and Wicken Phosphatic Deposits (Sedgwick Prize Essay for 1873) (1875) and "The Natural History of Phosphatic Deposits," Proc. Geol.
They are rich in grinding stone, and in phosphatic deposits.
The latest Cretaceous is the Ripley formation, which lies west of the northern part of the last-named, and, about Scooba, in a small strip, the most southerly of the Cretaceous - it is composed of coarse sandstones, hard crystalline white limestones, clays, sands, phosphatic greensands, and darkcoloured, micaceous, glauconitic marls; its greatest thickness is about 280 ft.
Accordingly it is more susceptible to exhaustion of surface soil as to its nitrogenous, and especially as to its mineral supplies; and in the common practice of agriculture it is found to be more benefited by direct mineral manures, especially phosphatic manures, than is wheat when sown under equal soil conditions.
Other essential conditions of success will commonly include the liberal application of potash and phosphatic manures, and sometimes chalking or liming for the leguminous crop. As to how long the leguminous crop should occupy the land, the extent to which it should be consumed on the land, or the manure from its consumption be returned, and under what conditions the whole or part of it should be ploughed in - these are points which must be decided as they arise in practice.
The phosphatic deposit has doubtless been produced by the long-continued action of a thick bed of sea-fowl dung, which converted the carbonate of the underlying limestone into phosphate.
In 1891 Mr Ross and Sir John Murray were granted a lease, but on the further discovery of phosphatic deposits they disposed of their rights in 1897 to a company.
05% phosphatic manures are generally found to be beneficial; with more than.
In the case of arable soils, where the amount of phosphoric acid determined by this method falls below 01%, phosphatic manuring is essential for good crops.
Phosphatic deposits are well developed among the Lower Eocene rocks.
Secondary products, such as glauconite, phosphatic concretions and manganese nodules, occur though less frequently than in the hemipelagic sediments.
Another group of phosphatic deposits connected with igneous rocks comprises the apatite veins of south Norway, Ottawa and other districts in Canada.
The phosphatic rocks which occur among the sedimentary strata are the principal sources of phosphates for commerce and agriculture.
Other kinds not distinctly hard and consisting of less rich phosphatic limestone, are known as " soft phosphate ": those found as smooth pebbles of variable colour are called " land pebble-phosphate," whilst the pebbles of the river-beds and old river-valleys, usually of dark colour, are distinguished as " river pebble-phosphate."
The phosphatic chalk and the phosphate sand, the latter resulting from the decomposition of the former.
Phosphatic nodules and concretions, with phosphatized fossils and their casts, occur at various geological horizons in Great Britain.
Bands of black nodules, highly phosphatic, are found at the top of the Bala limestone in North Wales; beds of concretions occur in the Jurassic series; and important deposits are known in the Cretaceous strata, especially in the Lower Greensand and at the base of the Gault.
The Cambridge Greensand, rich in phosphatic nodules, occurs at the base of the Chalk Marl.
At the base of the Red Crag in East Anglia, and occasionally at the base of the other Pliocene Crags, there is a " nodule bed," consisting of phosphatic nodules, with rolled teeth and bones, which were formerly worked as " coprolites " for the preparation of artificial manure.
The Lower Eocene rocks contain the chief phosphatic deposits of Algeria, those of the Tebessa region being the best known.
An oolitic structure is sometimes present, and the ores are generally phosphatic, and may contain perhaps 30% of iron.