Stose, Anna I. Jonas (earth scientist)

(1881-1974) American Field Geologist

Anna Jonas Stose was a geological pioneer who performed some absolutely incredible geological feats. She was a field geologist who mapped huge areas of the central to southern Appalachian Piedmont during a time when there were few women in the profession much less doing physically taxing work in the field. Most of her fieldwork was done on a reconnaissance rather than a detailed basis, which is intended to produce larger scale regional maps rather than the 5-by-6-mile quadrangle maps. Stose was one of the first to apply the then-advancing petrographic and structural techniques to the Appalachians. She began her mapping in southeastern Pennsylvania and adjacent Maryland with Eleanora Knopf. She continued her mapping southwestward into the crystalline rocks of Virginia throughout the Piedmont and Blue Ridge Provinces with some help from George Stose. She even mapped into North Carolina. Through this work she was a major contributor to both the Geologic Map of Virginia (1928) and the Geologic Map of the United States (1932), in addition to her numerous state and U.S. Geological Survey reports.

Stose defined many of the major rock units’ geologic structures in the central and southern Appalachians and the names are still used today.

Even her interpretations, which have gone in and out of acceptance over the years, are still essentially correct. Considering the adversity that she encountered in the lack of roads, encumbering clothing, and available transportation, in addition to prejudices against women performing such work, these accomplishments become almost unbelievable. She named the Brevard zone, a major structure of North Carolina, and interpreted it as a thrust fault. Unfortunately, she did not live long enough to see the magnitude of this structure as it was imaged on the COCORP seismic reflection profile across the southern Appalachians. It is estimated that this fault may have experienced hundreds of kilometers of thrust and strike-slip movement. She and Eleanora Knopf defined the Martic Line and proposed it to be a major thrust fault. Since then it was interpreted as a major strike-slip fault and a major plate boundary though the thrust fault interpretation has never been abandoned. Stose interpreted the Reading Prong of Pennsylvania to be a series of disconnected thrust fault bounded klippe, an idea that still remains accepted today. Not all of her ideas are still accepted but a surprising number are.

Stose’s naming and correlations of rock units from area to area are also surprisingly relevant. She traced the crystalline rocks of the Piedmont Province from Pennsylvania to Georgia and established the fundamental boundaries that still stand today. Many other boundaries were defined since this time but most of them are still debatable. She and Knopf defined and named the Conestoga Limestone a major unit of Pennsylvania. Stose named the major units of the Blue Ridge Province and many of the granite plutons both there and in the Piedmont. She also identified and named the enigmatic but important Mount Rogers volcanic sequence in southern Virginia. These units still retain their names and significance some 60 to 80 years after their identification by Stose. It is rare for interpretations in geology to remain for so long. This longevity is a tribute to the quality of her work. Two of the papers on this research include “Geologic Reconnaissance in the Piedmont of Virginia” and “Stratigraphy of the Crystalline Schists of Pennsylvania and Maryland.”

Anna I. Jonas was born on August 17, 1881, in Bridgeton, New Jersey. She was a descendant of one of the pilgrims who came to America on the Mayflower. Jonas grew up in Cape May, New Jersey, and attended the Friends Central School of Philadelphia. She received her college education at Bryn Mawr College, Pennsylvania, earning a bachelor of arts degree in 1904, a master of arts degree in 1905, and a Ph.D. in 1912. Her mentor was florence bascom, the grande dame of American geology. The friendship of Jonas and two of her classmates, Eleanora Knopf and Julia Gardner, is legendary. They were pioneers for women in geology. Jonas was an assistant curator at the Bryn Mawr Geology Museum in 1908 and 1909. Jonas worked at the American Museum of Natural History in 1916 and 1917 and as a geologist for the Maryland and Pennsylvania Geological Surveys from 1919 to 1937. She also worked as a contract geologist for the Virginia Geological Survey from 1926 to 1945. Jonas was a geologist with the U.S. Geological Survey from 1930 until her retirement in 1954. Anna Jonas married fellow geologist George Stose in September 1938 and took the name Anna Jonas Stose. George Stose died in 1960. Anna Jonas Stose died on October 27, 1974, of a stroke.

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