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Fig. 2 | Cognitive Research: Principles and Implications

Fig. 2

From: Spatially and temporally distributed data foraging decisions in disciplinary field science

Fig. 2

a Sample field site in White Sands, NM where geoscientists used the robot RHex (Qian et al., 2017) to measure surface-soil shear strength (inversely related to and hence a proxy for erodibility) along dunes with sharp moisture gradients. b For each shear test, the leg penetrated a few millimeters into the sand, and then dragged a thin layer of grains across the surface while measuring the mechanical shear strength of the sand. See Additional file 1 for a video of RHex performing the shear test. c Transect (black line) of a dune where measurement data were collected (picture from Qian et al., 2019). At the crest of the dune, where soil was driest because of its distance from the groundwater table (orange line), shear strength was expected to be low. As moisture increased on the stoss face moving towards the interdune, shear strength was expected to also increase before leveling off at the point of moisture saturation. This pattern of expected results is displayed in blue. Instead, geoscientists observed that shear strength decreased slightly as soil became more saturated nearing the interdune area just before levelling off (green line)

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