5. The Upper Peat Bed, about four feet below Ordnance datum and fairly constant in level. It ranges from one to two feet in thickness, and where fully developed it presents the following details:—
5 a. Laminated peat with logs of willow, fir and oak, passing down into
5 b. Light-coloured flexible marl composed of ostracoda with much vegetable matter.
5 c. Shell-marl composed principally of Limnaea, Bythinia, etc., with ostracoda and much vegetable matter. This seam must have been formed in a nearly freshwater tidal marsh; it yielded Najas marina, a plant now confined to Norfolk.
5 d. Peat with logs of oak, etc. A Neolithic worked flint was found by Mr Storrie in this seam, three inches below the shell-marl. This implement is a fragment of a polished flint celt, which seems to have been used subsequently as a strike-a-light. Two bone needles are said to have been found in this peat-bed during the construction of the first Barry Dock.
6. Blue silty clay with many sedges. From five to seven feet in thickness.
7. The Second Peat is an impersistent brown band, a few inches in thickness, composed mainly of Scirpus maritimus. It suggests merely that for the time plant-remains were accumulating more rapidly than mud.
8. Blue silty clay, like Nos. 6 and 4. In its upper part, immediately under the peat bed No. 7, it contains land and salt-marsh shells, Helix arbustorum, Pupa, Melampus myosotis, Hydrobia ventrosa. Upright stems of a sedge, probably Scirpus maritimus, occur throughout this bed as through all the other silts.
9. The Third Peat occurs at or close to the bottom of the dock, at 20 feet below Ordnance datum. It rarely exceeds eight inches in thickness, but is persistent. In several places it is made up almost entirely of large timber, both trunks and stools of trees, while in one section roots and rootlets extended downward from the peat into a soil composed of disintegrated Keuper Marl. Mr Storrie identified oak and roots of a conifer. On washing a sample collected at a few yards’ distance, I found it to consist of a tough mass of vegetable matter, principally sallow and reed, both roots and stems. It also contained seeds of Valeriana officinalis and Carex, and elytra of beetles. There was no evidence of salt water.
At this point it will be observed that the floor of Keuper Marl rises, and Bed 9 abuts against it. Beds 10, 11 and 12 lay below the dock bottom, and were exposed only in the excavation for the foundations of walls, etc. Fortunately, Dr Strahan was able to examine a good exposure of the important part of them.