General purpose of survey: During the period 1943 and 1944, the primary purpose was to locate, describe, sample, and generally evaluate the SOM-vanadium mineralization in the western Carrizo Uplift and Chuska Mountains Areas. To this end, the areal geology of the areas, with emphasis on the Salt Wash member of the Morrison formation, was mapped. The triangulation and the laying out of leased plots were supplemental parts of this work. The field work in 1945 was for the purpose of collecting additional and supplemental geological data in order to complete the record and to calculate the ore reserves of the areas.

This report presents maps on the geology of the Western Carrizo Uplift and the Chuska Mountains of Arizona in the Northern Navajo Indian reservation.

Introduction: Vanadium ore is being mined at many places in western Colorado, southeastern Utah, northeastern Arizona, and northwestern New Mexico (fig. 1). Eight mills in this region produced about 4,300,000 pounds of V2 05 in 1942, representing about 90 percent of the vanadium obtained from domestic sources. Although ore production has mostly exceeded mill capacity since 1937, production during the last half of 1942 averaged only about 19,000 tons or ore a month, whereas the capacity of these mills total about 22,000 tons a month. At the expected rate of ore production, ore stockpiles will be exhausted sometime in 1944, and these mills will then have excess capacity. With more intensive prospecting than now practiced, however, it is believed that sufficient reserves can be indicated to sustain capacity operation of these mills for several years. This memorandum is prepared to specify those areas that are considered most favorable from a geologic standpoint for developing large reserves of vanadium ore by prospecting. It is based on intensive studies by the Geological Survey since 1939 in most of the areas that produce vanadium ore.