Editor's Summary

26 January 2006

Is there life on this planet?

Much of the Earth's land surface is blanketed with life, which strongly influences the processes shaping landscape; yet recent images reveal striking similarity between landforms on Mars and those on Earth. This raises a fascinating question: if we take a high-resolution topographic map and eliminate obvious signs of life from it, can we tell from topography alone that there is life on Earth? Bill Dietrich and Taylor Perron discuss our current understanding of the influence of biota on the processes controlling landscape form and evolution. They conclude that, while biotic processes affect landscape features at all scales, we cannot point to a landform that uniquely reflects the presence of life. A lifeless Earth would look different, but the difference would lie in the frequency distribution of certain landform properties. On the cover, clumps of vegetation introduce irregularities into a field of migrating sand ripples in Chile, but not in a uniquely life-dependent way.

ReviewThe search for a topographic signature of life

William E. Dietrich & J. Taylor Perron