Thickness of subaerial sand deposits at Saddle Canyon and Grapevine Rapid

Ground-penetrating radar profiles on sand bar at Grapevine Rapid on the Colorado River in Grand Canyon, collected with 100 MHz antennas. A) GPR profile oriented parallel to river; downstream direction is to the right. Hyperbolic reflections indicate presence of buried boulders at positions 5-25 m. B) GPR profile oriented perpendicular to river channel. Vertical, dashed line indicates where profiles cross.