Pett Level submerged forest recording weekend
18/10/2017 | Issie Barrington
An initial Saturday morning low tide foreshore foray was followed in the afternoon by a fascinating series of presentations by expert speakers in Rye, opened by Lara with her ever enthusiastic introduction to the CITiZAN project. Dr Scott Timpany then led us through the unexpectedly complex intricacies of the submerged forest and associated peat and clay layers, together with a summary of the findings of the study so far. Further funding is awaited to pursue research here – however, it is thanks to CITiZAN that these annual sessions to collect data are continuing. An intriguing insight into dendrochronology from Robert Howard of the National Tree Ring Dating Laboratory followed, with many questions from the floor ably expanded upon. A break for refreshments was accompanied by the opportunity to view wood and pollen samples through high magnification microscopes, which was most instructive! Finally Dr Claire Harris of the Lithic Studies Society took us on a quick hop through the Mesolithic – enlivened by photos of Germans in Mesolithic mode! - plus showed the classic diagnostic features of struck flints for tool manufacture.
The introductory walk on the beach across the submerged forest site by Cliff End provided an initial exploratory familiarisation with the site and its outcrop of peat riddled with a mesh of fallen tree trunks, branches and stumps. The paradox of such a range of dates in so short a distance across the peat down the beach was pointed out, with the most recent (Bronze Age) deposits exposed at the seaward edge of the peat shelf whilst the oldest (Mesolithic/Neolithic) occurred at the top of the beach. The range of tree species was remarked on, together with the fact that oak was easiest to discern by reason of its solidity: it is still hard and unyielding when prodded, whereas other species tend to feel slightly soft or give somewhat under pressure.
The 2017 recording team at Pett Level
A knowledgeable volunteer added to the interest by excavating shells of mollusc in the soft blue clay that intersperses the peat layers – apart from the ubiquitous piddocks of the modern shore (whose boring activities are responsible for the numerous cylindrical holes which pepper the wood in many places) said gent discovered a colony of peppery furrow shells, some still in life position, whose presence confirms brackish water, estuarine conditions. These molluscs live submerged in estuarine silts at a depth of a foot or so – and as a brackish water species provide conclusive proof of the habitat conditions of the time. The variety of habitat from freshwater, brackish and saline to dry land in a seemingly cyclical succession over relatively short timespans is one of the most intriguing factors that has emerged from the study so far – and a fragment of surviving reed leaf was found amid the peat and shown around by Lara (another species tolerant of brackish, or freshwater, conditions which is a typical stage in the succession from open water to wet woodland, and occurs too alongside estuarine margins).
Another fascinating discovery of the morning was a distinctly regular triangular piece of rock in a pool atop the peat, suggested as a possible anchor of unknown antiquity – albeit it had no hole for fastenings. Alongside was an irregularly shaped but distinctly striated lump of rock, with parallel furrows which could conceivably have been worn by rope action, although by what means and for what purpose is a trifle mysterious. The foreshore is full of enigmas always!
Sampling and recording
Sunday morning was the hands-on, get dirty session of the weekend where all the action to collect specimens and data for analysis was concentrated. Unlike last year, when trees outcropping in a given area of peat were recorded on a Tree Recording Form and a sample of the wood of each collected for identification, this year’s plan was more intensive. Three groups rotated around helping collect trunk slice samples suitable for dendro, fieldwalking in an attempt to find worked flint on the foreshore plus recording and sampling of a complete transect up the beach across the peat. It was a scene of intense activity in order to cram in and achieve as much as possible in a mere three hours before the incoming tide put paid to our efforts.
The samples for dendro involved excavating a small pit either side of a trunk so as to expose sufficient surface for the chainsaw to extract a slice through the heartwood and hopefully also encompass an outer edge with evidence of bark. Hard work digging out the peat with a spade was complicated by the holes filling up with water, but around six or so impressive plastic wrapped slices of tree trunk were successfully collected by the end of the session. One slice managed a perfect section through a piddock deep within the trunk, complete with protruding fleshy tongue!
Fieldwalking for flint was accomplished by quartering the edge of the eroding peat shelf in the hope of finding a piece of protruding worked flint. Back around 1900 a few blades plus an axe had been found in the area but the 1970s excavation of the cave high up the cliff face found nothing. Following this, the shingle beach below the cliff was carefully walked (which caused a certain degree of geological distraction for some of us!), but sadly nothing was found. For anyone familiar with this beach and the peat shelf this came as no surprise (it is the only beach in the south and east where I’ve never found anything remotely resembling unnatural or struck flint – and the one I’ve frequented by far the most!). The best possibility would probably be following stormy weather when the peat has been disturbed and after cliff falls for material from above, albeit the soil atop the cliff has an exposed eroding edge so may release material gradually, especially in rainwater run-off. (And any beach material could anyway have originated much further west, redeposited by the action of longshore drift.)
An exciting innovation today was the transect over the peat shelf inland from its seaward edge, 1m wide and for a distance of 15m. The procedure involved cleaning all the wood outcropping along the transect so it could be easily visually discerned, photographed and then recorded in plan form by measured drawing onto Permatrace, quadrat by quadrat up the beach. A sample of the wood from each individual trunk, branch, stump or fragment of wood was then taken and numbered for future species identification. It is not the intention to undertake dating of each specimen, however, so their contemporaneity will remain uncertain – but this will constitute a complete record of one section of the foreshore at the current peat surface. By not just concentrating on major trunks and stumps Scott was hoping to locate some smaller branches and perhaps find tangible evidence of surviving examples of alder buckthorn within the peat – the one woody species which has appeared in the pollen samples but not yet been found as remnant wood. Only by finding actual remains of the tree can it be proved that the species grew amid the forest below the cliffline now submerged – otherwise the pollen could have blown onto the peat from adjacent areas. (Alder buckthorn is a very small tree which prefers peaty soils.) Unfortunately the incoming tide prematurely terminated operations before recording of the transect was completed – an excuse to return perhaps??!
(Incidentally, the foreshore near Cliff End is fairly unique in having not rock pools, but tree branches in peat pools! Species in the the transect were typically a good growth of sea lettuce, wrack species [toothed wrack in my patch] and filamentous green algae – plus copious accumulations of mussels, together with a few minute crabs transported to the safety of adjacent pools. There was also a carpet of unidentified silt covered furry weed encrusting the wood within the pools.)
We finished off with a picnic at the top of the beach– altogether a great end to another super CITiZAN weekend organised by the indefatigable Lara! The weather had favoured us with ideal sunshine and it proved a most satisfying, instructive and enjoyable event – and the results are eagerly awaited . . !!