Thickness of Lavas on Mercury: Nasa Messenger Images, Date presented 29 Sept 2011

Date Presented: September 29, 2011, at a NASA Press Briefing Instrument: Mercury Dual Imaging System (MDIS) Of Interest: An example of how geologists estimate the thickness of lava flow deposits on Mercury. (Left) A fresh impact crater (Hokusai, 114 km diameter, 57.8° N, 343.1° E) provides the opportunity to measure the depth of its interior and the height of its rim above the surrounding terrain. (Right) A "ghost" crater (90 km diameter, 74.3° N, 335.7° E), a circular feature in the volcanic plains outlined by ridges, suggests that the outpouring of the volcanic plains have buried a preexisting impact crater. From an estimate of the height of the rim of the buried crater, the thickness of the lava covering the crater may be determined.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington