SHARAD detections of the lava flow unit interfaces within the Amazonian volcanic terrain. The colored tracks depict the two-way round-trip delay time of basal reflectors mapped in SHARAD data. (a) The youngest lava flows detected on Mars. Reflector group is centered at 151.7°E, 5.8°N. (b) Lava flows in the vicinity of 10.1 km Zunil crater. Reflector group is centered at 166.2°E, 8.3°N. In solid rock (assuming an ε′ of 9), a round-trip delay of 1 μs corresponds to a (one-way penetration) thickness of 50 m.