In June of 1937, Child and Thorneycoft made another attempt at vitrification at Rahoy, the site of a Dun at the entrance of Loch Teacuis in Scotland. This time, they used the actual materials used in construction at the Dun, which had contained signs of ancient vitrification. The wall was built, facing west, across a trench which had been dug into the vitrified rampart during earlier excavations. The construction of the Rahoy wall was hampered by a lack of suitable timber and was considerably smaller than the one created at Plean Colliery. The height of the wall ranged between 6.5 feet in the front to 4.25 feet in the rear and angled inward. The depth was approximately 9 feet with a rise of about a foot and a half from the front to the middle
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the structure was lit. With a light breeze for the northwest, it soon began to smolder and produce a blue smoke, indicating the wood was being turned into charcoal. Three hours later, a red glow was visible between the spaces in the rock, and blue smoke continued to be emitted. Two hours later, believing the wind to be cooling the rockface, additional kindling was added in an attempt to increase the heat to the outer surface, but seemed to have the opposite effect. Before long the red glow ceased to be visible. By 10:30 p.m. no more smoke was seen. Viewed from the top, where the sod had burned away, revealed stones that were still glowing red. Logs were piled on top which caught fire almost immediately. By the next morning the fire had burned itself out. The wall had not collapsed on the outer face, but had buckled somewhat, sagging as much as 18 inches on one corner. Virtually all the timber had burned away, save the logs on the very bottom. Charcoal was visible, and some wood ash had fused to the rock. After clearing away the loose rock, between the 4th and 3rd levels vitrification had occurred in the center and became more numerous as they reached the area between the 3rd and second level. There they discovered a mass estimated to weigh 250 lbs, which broke apart when moved, producing 5-10 lb. lumps of virtually solid vitrified rock. Childe and Thorneycroft concluded that while the less than ideal circumstances they were presented with …show more content…
After consulting many experts, a decision was made to use the basic timber-laced murus gallicus model used in the previous experiments by Childe and Thorneycroft. A decision, based on costs, was made to use cheaper pine scrap lumber rather than hardwood timbers such as oak. The scrap lumber included a few metal fasteners still imbedded in the wood, such as nails and screws. Most of the wall’s granite facing-stones were salvaged from a nearby demolished drystone dyke. For the filler at the heart of the wall, the bulk consisted of head-sized pieces and chips of gabbros, a course grained intrusive igneous rock (https://geology.com/rocks/gabbro.shtml) chosen for its “ready flow” properties at lower temperatures. Additional filler was obtained consisting of a metamorphic rock, a quartzose mica-schist, in similar sizes.
the structure was lit. With a light breeze for the northwest, it soon began to smolder and produce a blue smoke, indicating the wood was being turned into charcoal. Three hours later, a red glow was visible between the spaces in the rock, and blue smoke continued to be emitted. Two hours later, believing the wind to be cooling the rockface, additional kindling was added in an attempt to increase the heat to the outer surface, but seemed to have the opposite effect. Before long the red glow ceased to be visible. By 10:30 p.m. no more smoke was seen. Viewed from the top, where the sod had burned away, revealed stones that were still glowing red. Logs were piled on top which caught fire almost immediately. By the next morning the fire had burned itself out. The wall had not collapsed on the outer face, but had buckled somewhat, sagging as much as 18 inches on one corner. Virtually all the timber had burned away, save the logs on the very bottom. Charcoal was visible, and some wood ash had fused to the rock. After clearing away the loose rock, between the 4th and 3rd levels vitrification had occurred in the center and became more numerous as they reached the area between the 3rd and second level. There they discovered a mass estimated to weigh 250 lbs, which broke apart when moved, producing 5-10 lb. lumps of virtually solid vitrified rock. Childe and Thorneycroft concluded that while the less than ideal circumstances they were presented with …show more content…
After consulting many experts, a decision was made to use the basic timber-laced murus gallicus model used in the previous experiments by Childe and Thorneycroft. A decision, based on costs, was made to use cheaper pine scrap lumber rather than hardwood timbers such as oak. The scrap lumber included a few metal fasteners still imbedded in the wood, such as nails and screws. Most of the wall’s granite facing-stones were salvaged from a nearby demolished drystone dyke. For the filler at the heart of the wall, the bulk consisted of head-sized pieces and chips of gabbros, a course grained intrusive igneous rock (https://geology.com/rocks/gabbro.shtml) chosen for its “ready flow” properties at lower temperatures. Additional filler was obtained consisting of a metamorphic rock, a quartzose mica-schist, in similar sizes.