The Wissahickon Controversy: Florence Bascom vs. Her Students

In the history of science there have been many cases where former students have broken with their mentor, often in the process of establishing their own ideas and pursuits. The resulting ambivalence and conflict can be likened to that which occurs in a family when offspring separate from parents and establish their own identities. However, there are relatively few instances in the history of science when this process has taken place in a context in which both mentor and students were women. Such was the case with Florence Bascom and her protégées at Bryn Mawr College, Anna Jonas (Stose) and Eleanora Bliss (Knopf). The controversy began over the relative age of the Wissahickon schist/gneiss, which was referred to the Ordovician in a paper on the Piedmont district of Pennsylvania published by Bascom in 1905. Jonas and Bliss became involved following the publication in 1916 of their joint doctoral dissertation on the relation of the Wissahickon to other formations in the Doe Run-Avondale region of Pennsylvania. In subsequent papers that came out in the 1920s, they sought to establish the existence of a pre-Cambrian "Glenarm series," including the Wissahickon, and introduced the concept of the Martic overthrust. This hypothesized fault was eventually extended by them and George Stose northward to New Jersey and southward to Alabama; the argument, which peaked in the 1930s, eventually extended to everyone concerned with Appalachian geology.