The dark circular seaweed-covered shape here on the shore is the remains of a crannog; crannogs are "partly or wholly man-made islands which supported timber buildings". There are other crannogs in the inner estuary of the River Clyde, at Erskine (NS4572 : Erskine Crannog
), Langbank East (NS4073 : Westferry Crannog
), and Langbank West (NS3873 : Langbank west crannog
), but the one at Dumbuck is by far the best-preserved. [For a concise account of this site, see "Archaeology around Glasgow", Susan Hothersall, Glasgow Archaeological Society, 2007.]
Recent research has dated the remains to between 200BC and 200AD, and suggests that it was a water-side platform rather than a dwelling [A.G.C. Hale, "Scottish Marine Crannogs", 2004, Oxford].
There may have been a timber building here standing out on the platform, set a little way out from the shore. There was also a dug-out canoe moored nearby (described by the original excavators as "the great war canoe"), and an oak ladder, four metres in length, for getting to the canoe (at the time of writing, the ladder could be seen on display in Kelvingrove Museum, forming part of the "Scotland's First People" exhibition; as I recall, the wood was very blackened from age, but the structure of the ladder was intact).
The platform here was about 50 feet wide, and it is still possible to see the remains of more than twenty oak piles arranged in a circle - they can be seen as a ring of wooden stumps protruding above the mud. Within that circle, some of the horizontal timbers of the platform can also be seen. Outside the circle of piles was a stone and timber breakwater.
The site was excavated in 1898 by the Helensburgh Naturalist and Antiquarian Society; this is the same association who excavated Dumbuie Dun in 1895 - see: NS4275 : Dumbuie Dun
. Just as with that earlier dig, the crannog site was liberally "salted" with fascinating objects that caused great controversy at the time, and which are now known to be fakes. [For more on that topic, see "Controversy on the Clyde - Archaeologists, Fakes and Forgers: The Excavation of Dumbuck Crannog", by Hale and Sands, RCAHMS, which also gives a detailed description of the site, describes how the crannog would have looked when in use, and includes an extensive list of references for further reading.]
The site has been excavated more recently: in the 1990s, and in 2000.
My excursion to this site was planned to coincide with a particularly low tide. The crannog is set on mudflats, rather than a sandy beach, and it is often submerged, being completely uncovered for only a few hours at low tide.
In the foreground of the photo is a little burn which, at the time of the first excavation in 1898, was known as the Witches Plantain Burn; the burn used to flow past the other side of the crannog, and its old course (not visible in the photo) can still clearly be seen there, marked by long straight line of seaweed-covered stones.
Related articles about this crannog: NS4173 : Dumbuck Crannog from the south
, NS4173 : Dumbuck Crannog - remains of timber piles (south-east)
, NS4173 : Dumbuck Crannog - remains of timber piles (north-east)
, NS4173 : Dumbuck Crannog - the remains of the platform
, and NS4173 : Former course of the Witches Plantain Burn