Volcanic landscape, satellite image. North is at upper left. Desert sands are yellow, and volcanic rock is dark grey. The patches of yellow on the volcanic rock are summits of volcanic cones that are part of this lava field. The area is Pinacate National Park in Mexico's Sonora Province, close to the Pacific coast. Among hundreds of volcanic vents and cinder cones are rare maar craters, formed when rising magma met underground water to create pockets of steam that blew nearly circular holes in the overlying crust. Sand dunes are across bottom, and a dry river bed is at upper right. The area shown in this image is around 60 kilometres wide. The image data was obtained on 5 December 2002, by the Landsat 7 satellite.