COMMENT: Late Oligocene–early Miocene Grand Canyon: A Canadian connection?

Comment on “Apatite He/He and (U-Th)/He Evidence for an Ancient Grand Canyon”

Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) use thermochronometry to propose that the western paleo–Grand Canyon was nearly as deep 70 million years ago (Ma) as today. However, lithologies, facies relations, geomorphology, and paleotopography of Miocene interior-basin deposits near the mouth of the Grand Canyon show that no paleocanyon existed in t...

Comment on "Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon".

Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon-70 versus 6 million years-can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocan...

The Biogeographic Significance of a Large, Deep Canyon: Grand Canyon of the Colorado River, Southwestern USA

Late Miocene River Euphrates

1 Department of Geography, Harran University, 63300 Şanlıurfa, Turkey 2 Isotope Geosciences Laboratory, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA 3 Department of Geology, Çukurova University, 01330 Adana, Turkey 4 Faculty of Mathematics and Computing, The Open University, Eldon House, Gosforth, Newcastle-upon-T...

Wintertime Boundary Layer Structure in the Grand Canyon

Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon’s entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountai...