Pleistocene geomorphology and geochronology of eastern Grand Canyon: linkages of landscape components during climate changes

The linkages among hillslope-vegetation changes, elevation, and the timing of late-Quaternary fluvial-system aggradation in the Mojave Desert revisited

“…Quaternary deposits of the southwestern US are dominated by valley-floor-channel and alluvial-fan deposits and their associated terraces that record multiple regionally correlative episodes of aggradation, channel incision, and terrace abandonment (Christensen and Purcell, 1985;Bull, 1991;Harvey et al, 1999;Menges et al, 2001;McDonald et al, 2003;Anders et al, 2005). What drives these aggradation and incision episodes has been a fundamental question in the geomorphology and Quaternary geology of the southwestern US for decades.…”

Rates of river incision and scarp retreat in eastern and central Grand Canyon over the past half million years: Evidence for passage of a transient knickzone: REPLY

“…They did not take issue with our observation that short-distance transport in Colorado River tributaries is insufficient to round the pebbles present in several outcrop P1 lenses (see p. 645 of Abbott et al, 2015). Nor did they address our favorable comparison of those lenses' lith ology with that of terrace gravels near Tanner Rapid that Anders et al (2005) and Crow et al (2014) identified as Colorado River gravel (see our fig. 13).…”

Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

“…These cool, wet periods are marked by high pluvial lake levels (e.g., Currey et al, 1990;Matsubara and Howard, 2009;McGee et al, 2012;Oviatt, 2015), mountain glacier advances prior to the onset of the Bølling-Allerød (e.g., Owen et al, 2003;Guido et al, 2007;Orme, 2008;Refsnider et al, 2008Refsnider et al, , 2009Brugger, 2010), increased landsliding in the Rio Grande basin between ∼ 21.2 and ∼ 14.5 ka (Reneau and Dethier, 1996), deposition of valley fills in the Colorado River (Pederson et al, 2013), and speleothem growth (e.g., Polyak et al, 2004;Oster and Kelley, 2016). The warmer Bølling-Allerød and Holocene correspond to records of mountain glacier retreat (Guido et al, 2007;Laabs et al, 2013;Munroe and Laabs, 2013) and strath terrace formation due to river incision (Anders et al, 2005;Cook et al, 2009). While anomalous records, such as speleothem growth ∼ 14 ka during the Bølling-Allerød (Polyak et al, 2004), complicate the picture of past climate in the southwest, the general pattern of climate change closely mirrors that observed in the Greenland ice core records (Benson et al, 1997;Svensson et al, 2008;Asmerom et al, 2010;Wagner et al, 2010).…”

“…Combining these meltwater routing patterns with proglacial lakes and changing land cover will allow equations designed to predict sediment yield from large catchments to be employed for a continental-scale paleo-sediment-discharge reconstruction (following Overeem et al, 2005;Kettner and Syvitski, 2008;Pelletier, 2012;Cohen et al, 2013), with modern control provided by present-day sediment yields (Table 1). These sediment discharges can be compared with records of deposition (e.g., Andrews and Dunhill, 2004;Breckenridge, 2007;Rittenour et al, 2007;Williams et al, 2010) and geomorphic change (e.g., Dury, 1964;Reusser et al, 2006;Knox, 2007;Bettis et al, 2008;Anderson, 2015). The need to properly compute past lake and land cover motivates continued work with climate-and water-balance models (e.g., Collins et al, 2006;Matsubara and Howard, 2009;Liu et al, 2009;He, 2011;Blois et al, 2013;Fan et al, 2013;Ivanović et al, 2016a), which can in turn be used to improve past drainage basin and discharge reconstructions.…”