Looking for Orkney's woodland - study of submerged forest sites in Orkney
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Looking for Orkney’s Woodland: Investigating Submerged Forest Sites on Orkney
Transcript of Looking for Orkney's woodland - study of submerged forest sites in Orkney
Looking for Orkney’s Woodland:Investigating Submerged Forest Sites on Orkney
Introduction
Submerged forests across the UK Submerged forests have
been observed and recorded since the late 17th century e.g. Plot 1686 at Formby
Period of fascination during the 19th to the early 20th centuries e.g. Reid 1913
Few studies since but those of note include: Severn Estuary Formby Westward Ho! Langstone Harbour Bouldner Cliff Thames Estuary
After Bell, 1997 p59
Lost lands Much of the fascination
of the early studies was due to the hypothesis that these deposits existed due to the sinking of the land.
This gave rise to romantic theories linking these remnant woodlands with ancient lost lands.
One example of this is that of submerged forests in Cornwall being linked to the lost land of Lyoness, where King Arthur met his end.
Submerged forests across Orkney In Orkney studies of
submerged forests have taken place since the early 19th century.
Of particular note were the exploits of Walter Traill Dennison.
More recent studies have taken place in intertidal peat areas across Orkney, such as: Keatinge and Dickson
1979 Buckland et al 1998 de la Vega-Leinert et al
2000, 2007 Sharpe 2014 Walter Traill Dennison
HERO
A lost land in Orkney – RSL change Relative Sea-Level
(RSL) changed appreciably during the Early Holocene period.
Led to the submergence of a large proportion of previous terrestrial land in Orkney.
Work to understand the impact and dynamism of this change is currently being undertaken by the Rising Tide Project Group.
HEROES
Illustration courtesy of C. Wickham-Jones and Rising Tide Group
Pollen studies across Orkney There have been a number
of pollen studies across Orkney providing us with a solid base of information for environmental change.
However, the majority of studies have taken place in West Mainland.
Therefore still a wide scope for work outwith this area.
Particular problem is finding sites that contain evidence for Late Holocene Environmental Change
Woodland information from Previous Work
Woodland established on Orkney at c. 8000 cal BC
Initial pollen studies suggested a cover of birch and hazel scrub woodland (e.g. Keatinge and Dickson, 1979).
More recent pollen studies suggest “true-woodland” did exist in some areas (e.g. Farrell, 2009).
Charcoal evidence from archaeological sites also supports this nomination of “true woodland” (e.g. Dickson, 2000)
Evidence for primary and secondary clearance of woodland (Farrell 2009; Farrel et al, 2013)
Woodland information from Previous Work
Pollen and charcoal studies from Orkney have revealed evidence for at least 17 tree types to have been present on Orkney during the prehistoric period.
These include: Alder Pine Willow Oak Hazel Birch Ash Elm Blackthorn Apple-type
(apple/pear/hawthorn)
Submerged forests?
Much of the current evidence we have then for prehistoric woodland is from pollen and charcoal studies.
So what happened to submerged forests?
What has happened to the pioneering work of our hero Walter Traill Dennison?
?
Pollen studies within submerged forests
Using Michelle Farrell’s study as a basis we can see that there have been: Approx. 30 pollen
studies across Orkney Of these 3 have been
on intertidal peats. With only 1 from a
submerged forest site.
It’s not all bad news
Projects such as Rising Tides have taken samples through and identified areas of submerged forests in areas across Orkney.
On-going work in places such as the Bay of Moaness on Rousay have used multi-proxy approaches on a submerged forest site.
Orkney Beach Combers are also finding new sites, which increase the number for study.
However, there is still a lot of scope for further work to be done… HOORAY!
HEROES
OWL Project
Orkney’sWooded Landscape
(also known as Scott’s Hobby Project and yes, yes we still need to work on the logo)
What can we learn? Pollen and charcoal studies have provided a
picture of the tree types that were present on Orkney during the prehistoric period.
However, we still know little about the character of these woodlands in terms of canopy composition (stands, openness etc.), physiognomy and field layer.
We also know little about how the woodland responded to environmental changes such as storminess, changing sea-level and groundwater tables, anthropogenic activity and faunal activity.
Essentially we want to know what did they look like and did they look like how we picture them to?
Dense woodland
Scrub woodland
Wet woodland
Park woodland
Mosaic woodland?
OWL Methods Taking a multi proxy
approach to sites of intertidal peats with submerged forest.
Includes: Auguring & Survey Tree recording Wood identifications Pollen Non-pollen palynomorphs Waterlogged plant
remains Macroscopic and
Microscopic charcoal Beetles
Sites in Orkney
OWL sites to date
Bay of Ireland
Bay of Moaness
Bay of Moaness, Rousay Follows the work of
Buckland et al 1998 who undertook stratigraphic investigation of the sediments, together with insect, mollusc, faunal bone and pollen analysis.
Michael Sharpe & ST recorded the submerged forest tree remains and undertook waterlogged plant remains analysis of the associated peat layers.
Bay of Moaness, Rousay Results so far…
Tree remains all identified as willow, with seed evidence suggesting they are grey willow.
Wood fragments, seeds and pollen of birch indicates this tree was present prior to willow and then died back.
Seed and pollen information indicate a ground flora dominated by sedges with meadowsweet, stinging nettles, rushes and common tormentil
Macroscopic and microscopic charcoal shows evidence for woodland burning.
Insert tree picture
Bay of Ireland, Mainland Submerged forest was
recorded and sampled. Exposed intertidal
peats were GPS surveyed along with tree remains.
Auger survey of the intertidal peats undertaken.
Peats sampled for waterlogged plant remains, pollen & NPP, and C14 samples.
Bay of Ireland, Mainland All trees recorded and
sampled were willow. Pollen, seed and wood
evidence shows that birch was also a component of the woodland.
Pollen and seed information shows the presence of halophyte vegetation indicating an area of salt marsh was probably close by.
Ground flora evidence includes: sedges, marsh woundwort and curly dock.
Top date for peat of 4488-4356 cal BC - funded by the OAS.
Gaining a picture of the woodland at Bay of Ireland.
Anthropogenic Activity at Bay of Ireland In both the macroscopic
charcoal and microscopic charcoal records there is evidence for large increases in grass charcoal during the period of the submerged forest.
This indicates that Later Mesolithic people were burning the wetland.
Wetland burning by Mesolithic communities also recorded in the Severn Estuary and at Starr Carr, North Yorkshire.
Reasons may include: Attract wild fowl & fauna Prevent encroachment of
woodland Manage the height and
denseness of tall herbs and reeds
Anthropogenic Activity at Bay of Ireland Oak ‘plank’ discovered by
Ted Pollard in 2013 – 3.5m in length.
‘Plank’ appears to be worked and is probably the first oak artefact discovered in Orkney.
Date from OAS indicates it is Later Mesolithic.
Purpose is so far Unknown Has potential to add to our
woodland story as well as add to our knowledge of Later Mesolithic communities.
Further work to come on investigating it’s use and age.
Anthropogenic Activity at Bay of Ireland No visible signs of working,
although preservation has been affected by tidal scouring, erosion and breakage.
Confirmed as part of an oak trunk.
At some point the trunk split into two trunks with the larger trunk subsuming the smaller one. This led to fault line running through the trunk.
Deliberately put into the peats probably in order to soak the timber in order to make it workable.
Fault line may have led to abandonment of timber.
Purpose still unknown but may have been structural or for use as log boat etc.
Future Work Further fieldwork taking place in five locations
this summer.
Otterswick Bay
Greameshall Bay
Berriedale Woodland
Future Work
Look to see how the prehistoric woodland compares to that of relict woodland on Orkney at Berriedale Woodland, Hoy.
Undertaken through Vegetation survey
(CRACKLES Method) Pollen and non-
pollen palynomorph analysis
Threat of Coastal Erosion and Increased Storminess
https://www.youtube.com/watch?v=aXZq27V8ShI
