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Grand Falls, Arizona: Dune Field Sand Transport 2013 - 2016

October 15, 2020

As part of a NASA-funded study of sediment flux rates at a Mars analog site, we installed a suite of instruments in a small dune field near Grand Falls, Arizona. Data released in this report were collected from 10/28/2013 to 11/04/2016. The Grand Falls (GF) dune field is located on the Navajo Nation. It lies ~70 km NE of Flagstaff, AZ, 2 km east of Grand Falls, and just north of the Little Colorado River (LCR). The dune field consists of barchans, smaller dunes, ripples, and bare, indurated interdune surfaces; all features commonly found on the Martian surface. We measured sediment flux using a Sensit saltation sensor and a set of three Big Spring Number Eight (BSNE) passive sediment samplers, at 20, 50, and 100 cm above ground level (AGL). The samplers are weighing BSNEs (wBSNE) that automatically weigh and log accumulated sediment weight. The Sensit and wBSNE data were taken once per second, then averaged and logged at one-minute intervals. The experimental BSNE (xBSNE), designed and built by the maker of the wBSNEs, passively collects sediment at ~50 cm AGL and records data as time-lapse photos of the collection chamber taken at 15-minute intervals. Wind data was collected from a set of three anemometers (installed at the same heights as the wBSNEs) that sampled and recorded one-second intervals once per minute. Our instruments were positioned ~120 m downwind from an active barchan that migrates ~30 m/year. This research is funded by the NASA Moon and Mars Analog Missions Activities (MMAMA) program, project #NNH13AV781. Research was conducted with the permission of the Navajo Nation and the Leupp Chapter. Any persons wishing to conduct geological investigations on the Navajo Nation must first apply for and receive a permit from the Navajo Nation Minerals Department, P.O. Box 1910, Window Rock, Arizona 86515, telephone # 928-871-6588.