Sky tech: Laser scans shed new light on past
A new online exhibition shows images from new archaeological surveys of historical sites on Forestry Commission Scotland land.
The images were created using a variety of techniques including aerial laser scanning, terrain modelling and low-level aerial photography.
They show Iron Age forts and the remains of townships whose last residents were forced to move out during the Highland Clearances.
The image on the left is a plan drawn by Victorian antiquarian Sir Henry Dryden in 1870 of Caisteal Grugaig, an Iron Age broch, combined with a modern terrestrial laser scan of the site.
Brochs were large, towering roundhouses and remains of them can be found in the west Highlands, Caithness and on Orkney.
Caisteal Grugaig was constructed in Glenshiel in the first millennium BC, between 2,000 and 3,000 years ago.
The brightly coloured image on the right was created using laser scans done from the air and on the ground. It is Kraiknish Dun, a small 2,000-year-old Iron Age fort, on the shores of Loch Eynort on the west coast of Skye.
Little remains of the broch and ancient fort today.
A re-enactor dressed as a British red coat has been superimposed on a laser scan of Achlain Bridge at Invermoriston, near Fort Augustus, to give scale to the 18th Century crossing.
The bridge was built during a period of 18th Century military road construction in response to Jacobite risings.
The laser scan was done to help archaeologists to spot artefacts more easily and also to better understand the make-up of the structure.
Achlain Bridge and others in the area were constructed during road-building work supervised by Major William Caulfield, who succeeded the more famous Gen George Wade as the British military's chief road builder in 1740.
Looking like the surface of Mars, this is another laser scan of Kraiknish Dun on Skye. The image also shows the ruins of an 18th Century township and the remains of "lazy bed" rig-and-furrow field system agriculture.
The township at Kraiknish comprised of four roofed and six unroofed buildings. Many of these communities on Skye and other parts of the Highlands were cleared in the 18th and 19th centuries to make way for large-scale sheep production.
Known as the Highland Clearances, there were incidents of forced evictions which involved the thatch on the homes being set alight and the walls of turf and stone being pushed down.
Archaeologists have been surveying prehistoric cup and ring markings at Ormaig in Argyll since 2007.
Created from the Neolithic to the Bronze Age, the rock art has been found at other sites in Argyll and also the Highlands.
Archaeologists believe the markings may have been made for a number of reasons.
These include for rituals, as territorial markers or mapping the stars. Archaeologists have even suggested that they could be the "doodlings" of bored, ancient shepherds.
A terrain model of Castle O'er, a large Iron Age fort near Eskdalemuir in Dumfriesshire, was created by taking thousands of individual measurements.
The terrain model has been overlain by a traditional archaeological topographic survey made of the site in 1997.
Dumfries Museum holds various artefacts found at the fort, including part of a glass finger ring and a flint blade.
Archaeologists have also recorded the ruins of a traditional Highland home in a high resolution laser scan at Rosal in Sutherland. The remains of the longhouse can be seen in the foreground.
Every point in the image represents a laser beam hitting the ground.
Longhouses were long, low thatched roofed homes and few examples of the properties survive in the Highlands today.
People were first recorded living at Rosal in 1296. The township, which had about 15 to 18 longhouses, was clear by about 1818.