Alluvial cycles, climate, and puebloan settlement shifts near Zuni Salt Lake, New Mexico, USA

Abstract

Twenty‐seven 14C dates from alluvial deposits and soils exposed in modern arroyos near Zuni Salt Lake, New Mexico, provide evidence for past episodes of piedmont and valley entrenchment by low‐order ephemeral streams. We recognize two episodes of entrenchment at A.D. 900–1050 and A.D. 1300–1400 that correlate to other arroyo‐cutting events in the region. Episodes of piedmont and valley entrenchment are followed by approximately 200–300 years of aggradation until arroyos are filled and shallow flooding with expansive sedimentation returns, completing an alluvial cycle. Many alluvial cycles appear synchronous across much of the southern Colorado Plateau and are likely linked to changes in climate and flood regime. Flooding on small basin drainages near Zuni Salt Lake is related to the Southwest summer monsoon, a meteorological event that is poorly linked to El Niño. Alluvial cycles on small basin drainages affected indigenous floodwater farming by locally lowering water tables and reducing irrigable area during phases of entrenchment and contributed to the aggregation of Puebloan communities on the southern Colorado Plateau in the A.D. 1300s. © 2008 Wiley Periodicals, Inc.

Holocene flood histories in south‐western USA

“…It has long been recognised that Holocene climate variability played a central role in fl ooding, river behaviour and alluvial cycles in the south-west (Bryan, 1925;Haynes, 1968), as recently highlighted by Huckleberry and Duff (2008). There are, however, signifi cant differences in opinion regarding what type of climate change is responsible for shifts in fl ood regime, alluviation and channel entrenchment.…”

Temporal frequency distributions of alluvium in the American Southwest: taphonomic, paleohydraulic, and demographic implications

“…An apparent increase in the frequency of arroyo cutting beginning around 4500 cal yr BP is further argued to be related to ENSO variability and the frequency of El Niño events and floods (Ely, 1997;Waters, 2009;Waters and Haynes, 2001). Alternatively, alluvial cycles that do not correlate within or between watersheds are attributed to non-climatic factors such as erodibility, sediment load, and channel geometry (Huckleberry and Billman, 1998;Huckleberry and Duff, 2008;McFadden and McAuliffe, 1997;Waters, 1986). Radiocarbon frequency distributions are incapable of distinguishing the mechanisms that cause alluvial cycles, but they do identify the presence/ absence of sediments in the 14 C chronology.…”

Holocene alluvial sequences, cumulic soils and fire signatures in the middle Rio Puerco basin at Guadalupe Ruin, New Mexico

“…A.D. 900-1000 across the Southwest region as Hall (1977Hall ( , 1990 observed and as widely exemplified in many different watersheds by a number of authors (Miller & Kochel, 1999;Waters & Haynes, 2001;Waters & Ravesloot, 2001;Nials, 2003;Karlstrom, 2005;Onken, 2005;Onken & Van West, 2005;Huckleberry & Duff, 2008 (Onken, 2005;Onken & Van West, 2005). Similarly, Huckleberry and Duff (2008) have recognized two episodes of entrenchment near Zuni Salt Lake, New Mexico, at A.D. 900-1050 and A.D. 1300-1400, followed by 200-300 years of aggradation until arroyos filled and overbank sedimentation and sheet flooding resumed. These same authors (Huckleberry & Duff, 2008:122-124) also suggest that there is much widespread synchronicity of arroyo-cutting events in the New Mexican and southern Colorado Plateau area, which imply important hydrological changes concurrent with the prehistoric Puebloan occupation of this region, and that this could have a climatic origin.…”