This folder is part of the papers of William F. Foshag (1894-1956). He was a geologist who specialized in the study of the geology and mineralogy of Mexico. In 1919 he became Assistant Curator at the United States National Museum's Division of Mineralogy and Petrology. From 1929 to 1941 he served as Curator of the Division of Physical and Chemical Geology (Systematic and Applied), and from 1929 to 1948 was also Curator of the Division of Mineralogy and Petrology. From 1948 to 1956, Foshag was Head Curator of the Department of Geology and Acting Curator of the Division of Mineralogy and Petrology. Between 1926 and 1941, Foshag made several collecting trips to Mexico under the auspices of the Smithsonian's Roebling Fund. While serving as a representative of the United States Geological Survey in its cooperative work with the Mexican government, Foshag was able to study the eruption of the Paricutin Volcano in 1943. He made subsequent visits to Paricutin in 1944 and 1945 to observe the volcano. The present folder contains six handwritten and annotated data maps made by Foshag on graph paper. They show data on the geology of the Paricutín volcano. One has dates from January to November 1947. One map show a variation diagram and relation between the Paricutín's lava and an ejected bomb. Another map shows the variation of lava with time from 1943 to 1952. Another shows the composition of crystals extracted from a specific point to another.
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