From the mid-nineteenth through twentieth centuries, geologists attained a good, if imperfect, view of the development of the Colorado River and the Grand Canyon. Beginning in the late 1850s and continuing through the 1880s, fundamental concepts such as fluvialism, antecedence, and superposition were invoked to explain the development of the Colorado River. Early proposals envisioned the Colorado River as “old” relative to the surrounding landscape. Challenges to antecedence were slow to emerge, and it remained the most viable theory into the early twentieth century. At that time two distinct periods (and styles) of erosion were proposed: a plateau cycle with lateral stripping of strata and a canyon cycle of deep, vertical dissection. Beginning in the 1930s, newer ideas proposed that the Colorado River was “young,” having been integrated by sequential basin spillover, the timing of which was constrained by interior basin deposits lying across the mouth of the Grand Canyon at the Grand Wash Cliffs (the Muddy Creek constraint). The field entered a period of uncertainty related to the conflicting evidence for an old (Paleogene) river upstream from the Grand Canyon versus a young (Neogene) river at Grand Wash Cliffs. Results from a symposium convened in 1964 offered a solution with a poly-phase history for the Colorado River. The poly-phase theory suggested that the river formed in a complex manner by the integration of two separate drainages, although some aspects became untenable. Efforts to resolve outstanding dilemmas from 1964, such as the ages of the Colorado River and the Grand Canyon, have ultimately led to a modern resurgence in research.
- Received 12 July 2013.
- Revision received 4 January 2014.
- Accepted 5 February 2014.
- © 2014 Geological Society of America