PETIT-FOURS RATHER THAN LAYER CAKES: AMERICAN GEOLOGISTS’ THINKING ON STRATIGRAPHY IN THE FIRST HALF OF THE NINETEENTH CENTURY

American geologists in the first half of the nineteenth century were almost uniformly unwilling to adopt the stratigraphic divisions and nomenclature emerging in Britain at that time.

Some of this resistance was rooted in philosophical, even political, perspectives on the propriety of applying European names to American rocks. Beyond the cultural objection to applying European nomenclature to American phenomena, Americans quickly came to understand that the American rock record was often more clear and complete than that of Europe. If a single universal system was to be developed and applied around the globe, should it not, they asked, be based on the “better” American rocks rather than the disturbed and degraded European strata?

More importantly, Americans believed that fundamental questions about how to build a sound system of nomenclature and how to determine true identity between two non-contiguous bodies of rock had to be settled before any wider conclusions could be drawn. Many of the American geologists long resisted the application of geographically specific terms in stratigraphic nomenclature, making the adoption of the Silurian, Cambrian, and Devonian doubly problematic. The relative weight to be given to lithological versus paleontological evidence was a critical question to be settled before true identity between distant bodies of rock could even be discussed. Ironically, Americans were sometimes tempted to adopt European nomenclatures not because they believed in the systems or the identity of the American rocks with those in Europe, but as a way out of the confusion created by the emergence of multiple American nomenclatures.

The grand synthesis of American geology at mid-century, James Dwight Dana’s Manual of Geology, makes clear that the early disputes were settled in favor of the frequent use of geographical names, the triumph of paleontological evidence and almost total abandonment of lithological evidence, and the conditional adoption of some of the British nomenclature. It is also, however, characterized by a constant insistence on the importance of the first-hand investigation of the specifics of local detail. Americans still preferred petit-fours over layer cakes.