| Description |
v, 183 leaves : illustrations, photographs, maps (some colored) ; 29 cm |
| Summary |
"The Problem. Washington County, Missouri contains a limited number of outcrops of pre-Cambrian igneous rocks, the majority of which are in the extreme southern part of the county. The known association of lead ore with buried or partially buried pre-Cambrian igneous knobs and ridges in this part of Missouri has led the St. Joseph Lead Company to prospect in areas known to contain these features. In its exploration program, the St. Joseph Lead Company has drilled a number of prospect holes which have encountered other occurrences of pre-Cambrian igneous rocks within the limits of Washington County. This drilling, correlated with magnetic and geologic maps, has expanded our knowledge of the distribution of igneous rocks in Washington County. The purpose of the present investigation was to identify as completely as possible the igneous rock types which occur in Washington County, to seek relationships between them in regard to position and origin, to delineate the topography of the pre-Cambrian surface, to study the effect of both primary and secondary mineralization upon the igneous rocks, and to determine the relationship between the occurrence of the igneous rocks and the mineralization, particularly the relationship of magnetite mineralization to the igneous rock types as revealed by direct observation and by magnetic anomalies"--Introduction, leaf 1. |
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