Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/372

 chiefly wing-cases, were found. Trunks of oak trees, some of them 60 feet long, were scattered through the peat, and had evidently fallen where they grew ; and from the characters presented by most of them, it would appear that they had grown close together. In this part of the bed, at the level of low water, and beneath a thick layer of moss, the remains of a fire were found. The author suggested that, from the small extent occupied by the remains of this fire, it was probably the result of human agency, as, if it had originated by lightning or by the friction of dry branches, it could hardly have been confined to so small an area.

The author inferred that no great change in the relative levels of different parts of the bed has occurred, because at the lowest eastern part the peat had been formed under water, branches and trunks of trees being imbedded in a stratum of grey clay, the wood being much of the same colour as the clay. In one large oak, 5 feet in diameter, there was a hole filled with acorns and hazel-nuts, many of the latter broken open at the end. This the author regarded as the store of a squirrel, and he remarked upon its being the sole trace extant of the existence of squirrels in the forests from which this peat was formed.

With regard to changes of level, the author stated that, whilst in other places an upward movement has been indicated*, the area examined seems to furnish evidence only of depression. Thus the surface of the peat in the supposed old channel of the river Hull is 12 feet below the level of low water, whilst the bed of the present river at South Bridge is only 6 feet below that level. The depression of the forest converted the land on which it grew into a marsh, where soft vegetable matter accumulated rapidly and soon covered up the fallen trees, the soundness of the timber indicating no long exposure to the weather. As the land continued to subside, the marsh was invaded by the waters of a tidal estuary, in which the Mollusca lived whose shells occur in the grey clay overlying the peat, and even in the peat itself. Of these the following forms occur: — Scrobicularia piperata, Cardium edule, Tellina solidula, Hydrobia sp., and Bullina obtusa, all, except the last, in great abundance. The arrangement of the trees at the east end of the dock was not such as to indicate that they had been deposited in a current having a constant flow in one direction. The bands of blue clay were bulged out above as well as below the logs ; and the author accounted for this by assuming that the logs did not yield to compression like the peat, from which, he thinks, an index of the compressibility of peat might be obtained.

Among the sections accompanying this account, two differ, in showing the Hessle Sand to thin out at the west end of the dock, from the section published in the Society's ' Proceedings '†. When the latter section was made, the excavations for the dock were not completed, and the sand underlying the silt in borings westward


 * Quart. Journ. Geol. Soc. vol. xxiv. p. 157.

† Quart. Journ. Geol. Soc. vol. xxiv. p. 182, fig. 14.