Late Holocene alluvial history of the Cuyama River, California, USA

Research Article| November 01, 2011 Late Holocene alluvial history of the Cuyama River, California, USA Stephen B. DeLong; Stephen B. DeLong † 1Biosphere 2, University of Arizona, PO Box 8746, Tucson, Arizona 85723, USA2Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, Arizona 85721, USA †E-mail: sdelong@email.arizona.edu Search for other works by this author on: GSW Google Scholar Jon D. Pelletier; Jon D. Pelletier 2Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Lee J. Arnold Lee J. Arnold 3Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca s/n, 09002 Burgos, Spain Search for other works by this author on: GSW Google Scholar GSA Bulletin (2011) 123 (11-12): 2160–2176. https://doi.org/10.1130/B30312.1 Article history received: 11 Apr 2010 rev-recd: 26 Feb 2011 accepted: 28 Feb 2011 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Stephen B. DeLong, Jon D. Pelletier, Lee J. Arnold; Late Holocene alluvial history of the Cuyama River, California, USA. GSA Bulletin 2011;; 123 (11-12): 2160–2176. doi: https://doi.org/10.1130/B30312.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Dryland river deposits are archives of past changes in fluvial-system form and process. Chronostratigraphic reconstruction of the late Holocene alluvial history of the Cuyama River in west-central California reveals past spatial and temporal variation in dryland channel form and process. The modern Cuyama River consists of a wide braided reach in the upper drainage basin, a narrower arroyo reach in the middle of the drainage basin, and a bedrock canyon reach in the lower drainage basin that drains to the Santa Maria coastal plain. Along the arroyo reach, late Holocene stratigraphy is well exposed and is the focus of this study. Between ca. 1700 and 350 yr B.P., two widespread deposits of tabular-bedded clay, silt, and fine sand were deposited, separated by a buried soil formed between 950 and 700 yr B.P. Channel incision occurred between 550 and 350 yr B.P. Next, deposition of massive to bedded sands occurred in a pattern alternating between poorly confined deposition on top of older deposits onto the broad valley floor, and channelized deposition along the valley axis inset into older deposits. The superposed deposits now underlie the main valley terrace, and the valley-axis deposits are preserved as inset fill terraces. Historical arroyo cutting then formed a 65-km-long arroyo ca. 150 yr B.P.Based on correlation to regional paleoclimate records, channel aggradation occurred during periods of relative aridity and low peak discharge events, while wet periods, possibly floods after drought, led to fluvial incision. These cycles are superimposed on a transition from a wide, silt- and fine-sand–dominated fluvial system to a modern, narrow, sand- and gravel-dominated arroyo channel. The relationship between times of fluvial process change and climate change in Cuyama Valley bears considerable similarity to other well-studied dryland rivers in the southwestern United States; however, the complex sedimentology and geometry of preserved fluvial deposits suggest that a wider range of fluvial modes occurred along the Cuyama River than has been reported in simpler cut-and-fill–dominated channels elsewhere. These spatial and sedimentological complexities underscore the need to link fluvial deposits and their bounding unconformities along a channel in order to fully understand the spatial and temporal evolution of ancient fluvial systems. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.