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I'll be bound that if we went down there we should find 'pipes' of soapy brecciated rock. Look, too," and I pointed to a series of worn flat slabs of stone that were placed on a gentle slope below the level of a watercourse which in some past age had been cut out of the solid rock; "if those are not tables once used to wash the 'stuff, I'm a Dutchman."
This ridge consists, as before remarked, of grey feldspathic lavas, and of red, brecciated, argillaceous tuffs, like the beds of the upper coloured series. The grey lavas contain numerous, minute, black, easily fusible specks; and but very few large crystals of feldspar.
Sometimes the limestone appears in a brecciated form, the fragments which are united together not consisting of foreign rocks but seemingly composed of the breaking-up of the Permian limestone itself, about the time of its consolidation. Some of the angular masses in Tynemouth cliff are two feet in diameter. Magnesian Limestone, Humbleton Hill, near Sunderland. Fenestella retiformis, Schlot, sp.
Bed 6, purplish, coarse-grained, hard sandstone, with broken crystals of feldspar and crystallised particles of carbonate of lime; it possesses a slightly nodular structure. Bed 7, blackish-grey, much indurated, calcareous mudstone, with extraneous particles of unequal size; the whole being in parts finely brecciated. In this mass there is a stratum, twenty feet in thickness, of impure gypsum.
C. A flat of coral-rock, covered at high water. D. A low projecting ledge of brecciated coral-rock washed by the waves at high water. E. A slope of loose fragments, reached by the sea only during gales: the upper part, which is from six to twelve feet high, is clothed with vegetation. The surface of the islet gently slopes to the lagoon. F. Level of the lagoon at low water.
The first little range is composed of a brecciated purple porphyritic claystone, with obscurely marked strata dipping at 70 degrees to the S.W.; the other ranges consist of a pale-coloured feldspathic porphyry, a purple claystone porphyry with grains of quartz, and a rock almost exclusively composed of brick-red crystals of feldspar.
These layers are sometimes brecciated and re-cemented, as if they had been broken by the slipping of the sand when soft. I did not find a single fragment of a sea-shell; but bleached shells of the Helix melo, an existing land species, abound in all the strata; and I likewise found another Helix, and the case of an Oniscus.
In the northern parts of this group there are some cliffs of gravel and of the boulder formation. The lavas attain a thickness of from two to three hundred feet; they are extremely variable in colour and nature, being compact, or brecciated, or cellular, or amygdaloidal with zeolite, agate and bole, or porphyritic with glassy albitic feldspar.
This lecture, called "The Iris of the Earth," stood first in Part III. of "Deucalion": and the work went on, in studies of the forms of silica, on the lines marked out ten years before in the papers on Banded and Brecciated Concretions; now carried forward with much kind help from the Rev. J. Clifton Ward, of the Geological Survey, and Mr. Henry Willett, F.G.S., of Brighton.
Seventhly: red sedimentary matter or sandstone like that of bed One, several hundred feet in thickness, and including jaspery layers, often having a finely brecciated structure. Eighthly: white, much indurated, almost crystalline tuff, several hundred feet in thickness, including rounded grains of quartz and particles of green matter like that of bed Six.
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