This image mosaic from NASA MESSENGER spacecraft shows an unnamed ridge in the northern volcanic plains of Mercury. Wrinkle ridges like this are interpreted to be tectonic in origin and are usually only found in volcanic plains. Six individual MDIS images are part of this mosaic. Instruments: Mercury Dual Imaging System (MDIS) Latitude: 79° Longitude: 118° E Scale: The ridge is approximately 140 kilometers (87 miles) long http://photojournal.jpl.nasa.gov/catalog/PIA19413