Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/371

 of the strata above the places in which these minerals occur, which would probably reveal the conditions under which they had been formed. They were probably produced by the decomposition of silicates in the overlying rocks during the percolation of water. This applies also to the Charlton locality.

Mr. Carruthers mentioned that allophane often fills the inflorescence of the Cycads of the Yorkshire Oolite, entirely destroying the vegetable structure, and that it also occurs in clay nodules from the coal-measures. Mr. Carruthers suggested that the decomposition of vegetable matter in clays might aid in the production of the mineral.

4. Notes on the Peat and Underlying Beds observed in the Construction of the Albert Dock, Hull. By J. C. Hawkshaw, Esq., F.G.S.

[Abridged.]

The author described the Albert Dock as extending east and west along the foreshore of the Humber at Hull, for a distance of 4000 feet. The total area excavated was about 30 acres. All the excavations were carried to a depth of at least 8 feet, and in some in- stances of 27 feet, below the level of low water.

Before the commencement of the excavations the Hessle Clay, peat, and overlying silt were met with in succession on the foreshore, the level of the top of the peat-bed at the west end of the area being about 3 feet above the level of low water, and its thickness from 3 to 4 feet. Eastward the bed followed the undulations of the clay without much variation in general level for half a mile, when it began to dip, attaining a depth of 12 feet below low-water level at the lock-entrance, and then rising again. From this depression of the peat-bed, and the appearance of the overlying silts, the author thought it probable that this had been an old channel of the river Hull, and that the upper part of the peat had been removed by scour. In support of this view he quoted the statements of antiquarian writers.

The peat rested directly on the Hessle clay, into which roots penetrated to a distance of 5 or 6 feet, generally following the direction of vertical joints, which gave the clay a tendency to split into prisms. These joints did not occur in the Purple Clay; and the author suggested that they may have been caused in the Hessle Clay by its drying by exposure before becoming covered with vegetation. The sides of the joints were grey ; and this colour pervaded all the clay that was intermixed with the peat and extended for a distance of from 1 to 2 feet into the overlying beds of silt. This grey tint probably resulted from the decoloration of the iron, due to deoxidation by the vegetable matter of the peat.

At its highest level, at the west end of the dock, the peat consisted almost entirely of vegetable matters, including large accumulations of moss, leaves, and masses of brushwood, layers of oak-leaves with acorns, hazel-nuts, and fir-cones. Numerous remains of Coleoptera,

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