Geosphere paper on Pliocene rapid sediment aggradation in the Colorado River
Becky Dorsey is third author on a paper in the February 2015 issue of Geosphere. Howard et al. investigate the early Pliocene river-laid Bullhead Alluvium, exposed along the lower Colorado River downstream of Grand Canyon. They find that it records a massive pulse of sediment aggradation shortly after integration of the Colorado River system. This rapid aggradation likely was caused by: (1) release of sediment stored along upper parts of the lower river corridor; (2) a wave of incision up western Grand Canyon; and (3) accelerated erosion of regolith, surface deposits, and nonresistant Tertiary bedrock on a relict Miocene landscape of the Colorado Plateau.