smaller ones near temporary sites in the canyon. "Home Base" pueblos in the nearby highlands on Cummings Mesa and Paiute Mesa are believed to have supported temporary farming and hunting parties, who used an extensive trail system in the main canyon which is still in use today. Natural resources for tool-making "Stone tool manufacturing appears to have been an important industry for the entire Glen Canyon region, perhaps one of the major reasons for occupation". Cryptocrystalline rocks fill the Pleistocene gravel beds on the Carmel platforms. Scattered lithic tools and materials indicate workshops of various sizes. There is a lack of siliceous material in the highlands, but tools are found there made from the gravel beds in the river. There are very few ground stone artifacts, such as manos, metates, and scrapers, found in the main canyon, since these tools are mainly found in the highlands. In the main canyon, a large number of chipped implements, ranging from small arrowheads to large knives, are found. Finished tools, and possibly blanks taken to the mesa, were probably used for trade. Archaeology Around 1956, archaeologists and biologists from the University of Utah and the Museum of Northern Arizona, using National Park research grants, planned an emergency excavation of Lower Glen Canyon, which was soon to be flooded by the new Glen Canyon Dam. Between 1958 and 1960, four investigative phases, combined with other surveys prior to 1957, discovered 250 archaeological sites within the canyon. The Lower Glen Canyon survey was completed in 1958. Excavations Excavations began during the summer of 1958 on 16 sites. A thesis emerged that prehistoric people living permanently on the highlands south of Glen Canyon and on the Cummings Mesa, farmed the Lower Glen Canyon on a seasonal basis, and gathered raw materials. To prove this thesis of seasonal habitation, criteria such as architectural units, locations of trail systems, occurrence of ceremonial structures, prevalence of burials, and position of natural and cultural strata were investigated. Four types of sites are described in the survey, classified as either open sites situated on rock terraces; talus sites on broken material below cliffs; shelter sites in protected areas under overhanging cliffs; and cliff sites beneath ledges or in caves and canyon walls. Open sites are the majority on both sides of the river. The majority of sites, mostly Navajo camps, feature lithic garbage or ceramics, or both. Talus sites are rarely