NASA Spacecraft Revealing More Details About Planet Mercury
Source: NASA RELEASE: 11-330
Excerpt: ...Scientists for decades had puzzled over whether Mercury had volcanic deposits on its surface. New data show a huge expanse of volcanic plains surrounding the planet's north polar region. These continuous smooth plains cover more than six percent of the planet's total surface. The deposits appear typical of flood lavas, or huge volumes of solidified molten rock similar to those found in the northwest United States. "If you imagine standing at the base of the Washington Monument, the top of the lavas would be something like 12 Washington Monuments above you," said James Head of Brown University…. Scientists also have discovered vents or openings measuring up to 16 miles (25 kilometers) across that appear to be the source of some of the large volume of very hot lava that has rushed across Mercury's surface….
www.nasa.gov/home/hqnews/2011/sep/HQ_11-330_Messenger_Images.html
www.nasa.gov/home/hqnews/2011/sep/HQ_11-330_Messenger_Images.html