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https://exhibits.library.illinois.edu/s/rbml/item/4004
- Title
- Geologic time, as indicated by the Sedimentary Rocks of North America
- Description
- Debates about the accuracy of Lord Kelvin’s estimate for the age of the Earth spurred an alternative approach among geologists that relied upon calculations of the rate of sediment accumulation and erosion. This method was less theoretical, and used direct observation and measurement, but still contained a large amount of assumption and conjecture. Charles Walcott illustrates the method here in “Geologic time, as indicated by the Sedimentary Rocks of North America” (Journal of Geology, 1893). The table shows the periods of Earth history with accompanying estimates of their duration. Walcott and others were drawing upon a practice that stretched back at least to the studies of sediment accumulation in the Rhine and Nile River deltas by Jean Andre de Luc and Déodat Dolomieu, respectively, and erosion of volcanic valleys in Auvergne by Nicloas Desmarest. The key difference was that Walcott’s scope was global, whereas the studies of these earlier savants were local. Ironically, Walcott’s total estimate for the age of the Earth is nearly the same as the one derived by Lord Kelvin; however, Walcott’s estimate yielded more detailed information about the longevity of each period. The ratios of their durations (except for the Archean and Algonkian) are surprisingly similar to ones accepted by modern geologists.
- Call Number (click link to view in library catalog)
- 550.5 JG
- See Also
- Full Text Available at JSTOR
- Authors
- Walcott, Charles
- Date
- 1893
- From the Exhibit
- In Search of Lost Time: Earth’s Chronology
- Publisher
- University of Chicago Press
- Location
- Chicago
- Language
- English
- Rights
- This item was originally published in the Journal of Geology. Intellectual property rights, including copyright, may reside with the materials' creator(s) or their heirs. This content was downloaded from JSTOR on 4/4/2023. JSTOR terms and conditions of use can be found here: https://about.jstor.org/terms/.
- Type
- Text
- Medium
- Article
- Bibliographic Citation
- Walcott, Charles. “Geologic time, as indicated by the Sedimentary Rocks of North America.” Journal of Geology 1, no. 7 (1893): 639-675.