I am currently describing the fish faunas of the Sucker Creek Fm, 14 million years old (14 Ma), Juntura Fm (11 Ma), Drewsey Fm (9 Ma), Danforth Fm (8 Ma), and Chalk Butte Fm (7 Ma) in southeast Oregon (Smith et al. 2013b). The goal of this research is to discover fish evidence for an ancient connection across southern Oregon between the Snake River Plain in southwest Idaho and the Great Valley of California. The 35 species of Miocene and Pliocene fishes of the Snake River Plain (Chalk Hills Fm (7 Ma) and Glenns Ferry Fm (4-2 Ma) show their closest affinities with recent fishes of the Great Valley, California (Smith et al. 2000), and Miocene fishes in Hopi Lake, east of Grand Canyon, but geological evidence for the Oregon connection is lacking (Spencer et al. 2008). Our recent work on Miocene fishes of the Lower Colorado River Basin makes it clear that those Great Basin fish had long been isolated from the upper Colorado Basin until the upper Colorado River spillover through Grand Canyon (5 Ma, Spencer et al. 2003; Smith et al. 2013) (contrary to a very influential recent publication (Dickenson 2013). Finding ancient river connections between the Snake River Plain in Idaho and the Great Valley in California as well as to the Colorado River drainage in Arizona is an exciting project that is crucial to many controversial parts of western U.S. geology, including, especially, the age of the Grand Canyon.
Dickenson, W.R. 2012 Rejection of the lake spillover model for initial incision of the Grand Canyon, and discussion of alternatives. Geosphere, 9:1-20.
Smith, G.R., N. Morgan, and E. Gustafson. 2000 Fishes of the Mio-Pliocene Ringold Formation, Washington: Pliocene Capture of the Snake River by the Columbia River. Papers Univ. Michigan Museum of Paleontology. 32:1-47.
Smith, G.R., R.E. Reynolds, and J.D. Stewart, 2013a Hydrographic significance of fishes from the early Pliocene White Narrows beds, Clark County, Nevada. Desert Symposium, 2013.
Smith, G.R., Stewart, J.D., Carpenter N.E., 2013. New fossil and recent Mountain Suckers and evolution of Pantosteus (Teleostei, Catostomidae) in Western United States. Occasional Papers of the University of Michigan Museum of Zoology Occasional Papers, 734: 1-59.
Spencer, J.E., and Pearthree, P.A. 2003, Headward erosion versus closed-basin spillover as alternative causes of Neogene capture of the ancestral Colorado River by the Gulf of California, in Young, R.A., and Spamer, E.E., editors, Colorado River Origin and Evolution: Grand Canyon Association Monograph 12, p. 215-219.
Spencer, J.E., Smith, G.R., and Dowling, T.E., 2008, Middle to Late Cenozoic geology, hydrography, and fish evolution in the American Southwest, in Reheis, M., Hershler, R., and Miller, D., editors, Late Cenozoic Drainage History of the Southwestern Great Basin and Lower Colorado River Region: Geologic and Biotic Perspectives: Geological Society of America Special Paper 439: p. 279-299.