|This figure shows two examples of younger lava channels that buried older lava tubes
on Mars. The boundary between the rougher appearing lava channels and the smoother
appearing lava tubes is outlined in black. Image A was taken by the High Resolution
Stereo Camera (HRSC) onboard the European Space Agency's Mars Express and image B
was taken by the Thermal Emission Imaging System (THEMIS) onboard NASA's Mars
Odyssey spacecraft. Print-resolution copy.
Credit: ESA and NASA