Letters to Nature

Nature 397, 586-589 (18 February 1999) | doi:10.1038/17545; Received 16 September 1998; Accepted 14 December 1998

Evidence for recent volcanism on Mars from crater counts

William K. Hartmann1, Michael Malin2, Alfred McEwen3, Michael Carr4, Larry Soderblom5, Peter Thomas6, Ed Danielson7, Phillip James8 & Joseph Veverka6

  1. Planetary Science Institute, Tucson, Arizona 85705, USA
  2. Malin Space Science Systems, San Diego, California 92191, USA
  3. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA
  4. US Geological Survey, Menlo Park, California 94025, USA
  5. US Geological Survey, Flagstaff, Arizona 86001, USA
  6. Cornell University, Ithaca, New York 14853, USA
  7. California Institute of Technology, Pasadena, California 91125, USA
  8. University of Toledo, Toledo, Ohio 43606, USA

Correspondence to: William K. Hartmann1 Correspondence and requests for materials should be addressed to W.K.H. (e-mail: Email: hartmann@psi.edu).

Impact craters help characterize the age of a planetary surface, because they accumulate with time. They also provide useful constraints on the importance of surface erosion, as such processes will preferentially remove the smaller craters. Earlier studies of martian crater populations revealed that erosion and dust deposition are important processes on Mars1, 2, 3, 4, 5, 6. They disagreed, however, on the age of the youngest volcanism7, 8. These earlier studies were limited by image resolution to craters larger than a few hundred metres in diameter. Here we report an analysis, using new images obtained by the Mars Global Surveyor spacecraft, of crater populations that extend the size distribution down to about 16 m. Our results indicate a wide range of surface ages, with one region—lava flows within the Arsia Mons caldera—that we estimate to be no older than 40–100 million years. We suggest that volcanism is a continuing process on Mars.