heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen. Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis. Bitumen is similar to the organic matter in carbonaceous meteorites. However, detailed studies have shown these materials to be distinct. The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of . Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands. History Ancient times The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley civilization, lined with it. By the 3rd millennium BC refined rock asphalt was in use in the region, and was used to waterproof the Great Bath in Mohenjo-daro. In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing. The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon. The long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis () was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent. Bitumen was used by ancient Egyptians to embalm mummies. The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake). In approximately 40 AD,