section of the loch is still hazardous due to slag lying close to the surface. The Dubbs Water was originally dug as a canal in the late 18th century for transporting coal and iron ore to the steelworks and to take finished products to their markets. Roads were unsuitable for transport of heavy goods at the time and the railways were in their infancy. Loch Riggs This was a collier's hamlet near the Maich Water. The Loch Riggs Colliery was abandoned in 1808 when the works were flooded. The rich coal seams ran under the loch and were never further exploited. In 1900 the old colliery waste was encountered by the navvies during the construction of the railway between Lochwinnoch and Kilbirnie. A nearby road was locally known as the 'Back-Stair-Heid' and it has been suggested that this refers to the location of a pit ladderway used to carry coal out of the mines before winding engines were in use. Geology The solid geology in the lower catchment area is carboniferous limestone. Higher ground to the North and South is mainly basalt. The drift geology includes a layer of peat to the North and boulder clay and lake alluvium over the lower catchment zone. Soils are alluvium to the North and Southeast, whilst to the East and West poorly drained non-calcareous gley soils predominate. Archaeology In 1868 a crannog, its causeway and up to four logboats were revealed at the south-west corner of the loch as a result of dumping of furnace-slag from the now closed ironworks, causing the lake-bed sediments to be pushed upwards so that the crannog and logboat remains were exposed above the surface of the water. A site known as 'The Cairn' was already recognised, being exposed during exceptionally low water conditions. The crannog and causeway are marked on the 1st edition of the OS 6-inch map (Ayrshire, sheet viii) at NS 3238 5356. Two of the boats were recorded in some detail. The most complete of the longboats was 18' (5.5m) in length, 3' (0.9m) in breadth and circa 2' (0.6m) in 'depth'; about 2' (0.6m) had been lost from the bow. The stern was 'square'. A tripod pit and a bronze ewer were found in one of the boats, now preserved at the Royal Museum of Scotland. These items were not contemporary with the logboat. The boat itself disintegrated rapidly on exposure to air.