by the South Carrier and Chilcotin tribes. They have lived in the area for hundreds of years, travelling when necessary to hunt and trap animals such as beaver, caribou, moose, and to gather plants and roots. Fishing camps were also established in the area. The Ilgachuz Range is, or was, an important source of obsidian for the South Carrier and Chilcotin tribes. Obsidian was greatly desired because very sharp arrowheads and cutting knives could be made from it. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture, creating razorlike edges. It was also used for jewelry. Anahim obsidian was traded extensively throughout the BC Interior and up and down the Coast from Bella Coola. Red ochre used in paint and decoration was also obtained from this area. Structure The Ilgachuz Range is the second largest shield volcano in the Anahim Volcanic Belt which includes other immediately nearby ranges, the Rainbow Range and Itcha Range. It stands at above sea level - slightly shorter than its neighbor, Rainbow Range. It has a diameter of . The Ilgachuz Range was created by two chemically separate magmatic periods; an early complex series of trachyte and rhyolite eruptions, and late extrusion of a sequence of basaltic lava flows. Evacuation of the volcano's magma chamber resulted in the failure of one or more centrally located calderas. It is divided into Precaldera, Dome Forming, Intra Caldera and Shield Forming assemblages. The Precaldera Assemblage is best exposed on the east side of Pipe Organ Mountain where it contains a bedded pile over 300 m thick of weakly consolidated, moderately to extremely different, pyroclastics, flows and deposits of uncertain origin. Colours range from mottled green to grey, yellow, ochre, red and white. A green tuffbreccia composed of pumice fragments, feldspar crystals and minor debris is recognizable in several areas. The Dome Forming Assemblages include most of the rhyolite domes, related flows and the Ilgachuz Comendite. The northerly domes are subcircular talus mounds of plate sized pieces of light to dark grey, slightly porphyritic, flowbanded rhyolite with minor obsidian. Massive to banded chalcedony blobs and veinlets are related with these domes. The southern domes are somewhat different in nature, comprising intrusive and extrusive phases of cream colored porphyries. The Sax Dome contains an upper portion of cream coloured, aphanitic to fine quartz porphyry felsite with abnormal green glass filled fractures,