Have proved beneficial from earliest times when prehistoric man developed first industry in Texas by mining flint deposits along the Canadian River. Items made from these quarries have been found over a large portion of the western United States. Slabs of dolomite from area were used to build sturdy, warm homes; interiors were coated with mixture of sand, clay and caliche -- an advance uncommon in prehistoric North America. Modern man has established 31 industries based on oil and gas, to take advantage of geological riches untapped by ancient man. (1970)