Sunday, 28 July 2013

To the Bronze Age in search of a Tsunami

In 2012 Druridge Bay’s ponds and wetlands teemed with invertebrates flourishing in the summer-long floods and were waist deep in rushes, grasses and herbs. This summer the ponds dry and crack in the July heat-wave, their wildlife hunkered down, plants desiccated or grazed as livestock can now reach the swards that were behind deep moats of unseasonal flooding last July. These two years capturing a powerful example of how the ecology changes, but the Bay currently offers a more striking example of changes through time and landscapes, but also of human continuity. Along the dune front at Low Hauxley Archaeological Research Services are leading a dig to record the Bronze Age burial sites that had been revealed as dune erosion cut into a burial cist. The dig, "Rescured from the Sea" has been a revelation. The occasional burial remains had been known for many years but the dig has unearthed two arcs of large stones, the half circle outline of a Bronze Age cairn (far edge of site in photo), the outer half having already been washed away by the tides gnawing at the dunes. A few metres inland, and unexpectedly, an Iron Age round house is traced in the sand (right, foreground), with at least two hearths and what one digger described as a crazy paving patio out the front. Stone Age finds have also appeared in the concreted sand base of the site, perhaps from the same people who left their foot prints in the peat beds which are occasionally unveiled when winter tides rip back the sand from the adjacent beach. The Bronze Age site looked across a kilometre of land to a distant shore line, a world of wet woodland populated by red deer, wild boar and huge wild cattle known as Aurochs, a world which has been preserved in the peat beds along the dune face (Blog, 5/12/2012 and 10/12/2012 ). The continued use (or perhaps revisiting) of the Hauxley site from Stone Age, Bronze age through to Iron Age is a compelling tale and perhaps one laced with startlingly sudden change. The archaeologists are now digging down at Hauxley to search for evidence of the North Sea Tsunami, which occurred ~8000 years ago, a tidal drive driven by colossal undersea sediment slides, the Storegga slides, off the east coast of Norway. The floods of 2012 and heat wave of 2013 are much smaller events, but work with the archaeology to show just how dynamic this landscape can be. The diggers happily show you around at 11am or 1pm everyday, so get along and take a trip through time

Friday, 19 July 2013

Cows, coypu and the ectozoochory taxi

A July heat wave has clamped down over England. Radio Newcastle asked people to text in with the temperature in their office or car; often over 30oC. Up at Druridge Bay the dune grasses are being spun into sward of the finest golds and silvers, bleached and glittering in sunshine. The ponds which last year were overflowing have largely dried. The few which retain a hint of damp have become a haven for cattle, a mini-migration. Here is a subsidence pond at the south end of the Bay, in a pasture field, the cattle homing in on the cool soil amongst the grasses and rushes left by the hay cutter. The cows seem to mark out the pond’s outline with a precision to match any surveying I could do. The drying out is compounded by heavy grazing and quite bit of pooing.
This pond was a verdant swamp of spike rush and jointed rush a year ago, but the clumps of rushes are now bitten down to stumps and the mud poached by hooves. I’d like to know if the livestock can carry pond life from site to site; ectozoochory, to give hitch-hiking on an animal its scientific name. Whilst the expansive bulk of cattle seem a likely form of transport smaller animals can be good vectors too. One of my favourite studies is of things washed from the fur of coypu living (or, had been living) in the Carmargue in the south of France. The coypu had been shot, not part of the study, but as a control programme and Aline Waterkeyn and her colleagues hosed down the corpses to see what the coypu had been carrying. Waterfleas and rotifers, midge larvae and worms, Ostracods and springtails all came off in the wash (Hydrobiologia, vol 652, pp267-271). The water-fleas were particularly species associated with aquatic plants, which fits the herbivorous habits of the coypu. I have a soft spot for coypu, having watched them when I grew up in East Anglia. They would come out of the wetlands and “moo”, slightly forlorn, as if aware of their unloved status. I tried coypu curry once too. The coypu are gone from England now, eradicated due to their impact on crops and river bank defences. Like the coypu of the Camargue the cattle of Druridge Bay are likely vectors, and they moo.

Monday, 8 July 2013

Bad year, good year. Or, perhaps the opposite

The photos above show the margins of a subsidence pond in one of the pasture fields north of Cresswell village. On the left hand side the pond in July 2012, as the record breaking wet summer swelled the wetlands throughout the Bay. To the right the same pond in July 2013, as the first proper heatwave since 2006 takes hold. The weather during 2012 was a startling combination, opening up with a lingering winter drought that broke in April, to be followed by weeks of high rainfall punctuated by occasional exceptional downpours. Homes were flooded, roads closed or washed away and crops destroyed. Wildlife certainly suffered, most conspicuously the familiar butterflies of summer with the often overlooked cabbage whites suddenly becoming things of rare and flimsy beauty. This year seems better, although the high summer skippers and brown butterflies are taking their time to first appear on the wing. But which pond looks in the best health? In 2013 the same pond is but a puddle, the rushes and grasses stunted and grazed. Admittedly in 2012 no sheep or cattle were kept out in the fields, instead taken inside to weather the weather, so this year the verdant grasses, including the likes of the very palatable Flote grass, (Glyceria fluitans), have been nibbled to stumps. Again, 2012 looks in retrospect, like a boon year for many of the wetland plants.