I plan to collect 1. Modern river sand samples: I will collect two samples from the modern drainages of Cañada de los Sauces (34.012305 N, 119.880841 W) and Cañada Christy (34.023580 N, 119.874380 W). These samples will be collected close to the mouth of the modern drainages but above the inter-tidal zone. I will target recently deposited sand identified by the presence of ripple structures closest to the main channel of the stream. 2. Sandstone samples: I will collect a total of 6 outcrop samples from Cañada de los Sauces from the sections described in Pinter et al., 2011 and Schumann et al., 2017, namely, SC15 (34.00933 N, 119.85402 W), and SC16 (34.01109 N, 119.87457 W). These sandstones are exposed in the walls of gullies carved by these streams. I plan to collect samples with a rock hammer and without any mechanized equipment. I do not plan to use any chemicals in the field. I will actively avoid any plant and small animal habitat. Ground disturbance is expected but this will be kept to a minimum as sampling depth is expected to be ~10-20 cm.

Approved