that it was in fact a meteor crater, but that interpretation was not well established until the mid-20th century. As part of his interest in crater origins, Gilbert also studied the moon's craters and concluded they were caused by impact events rather than volcanoes, although he wondered why the craters were round and not oval as expected for an oblique impact. The interpretation of lunar craters as of impact origin was also debated until the mid-20th century. Geomorphology He joined the Harriman Alaska Expedition in 1899. Two weeks after the 1906 San Francisco earthquake, Gilbert took a series of photographs documenting the damage along the San Andreas fault from Inverness to Bolinas. Gilbert is considered one of the giants of the sub-discipline of geomorphology, having contributed to the understanding of landscape evolution, erosion, river incision and sedimentation. Gilbert was a planetary science pioneer, correctly identifying lunar craters as caused by impacts, and carrying out early impact-cratering experiments. He coined the term sculpture for a pattern of radial ridges surrounding Mare Imbrium on the moon, and correctly interpreted them in 1893 as ejecta from a giant impact. Gilbert was one of the more influential early American geologists. Awards He won the Wollaston Medal from the Geological Society of London in 1900. He was elected as a member to the American Philosophical Society in 1902. He was awarded the Charles P. Daly Medal by the American Geographical Society in 1910. Gilbert was well-esteemed by all American geologists during his lifetime, and he is the only geologist to ever be elected twice as President of the Geological Society of America (1892 and 1909). Because of Gilbert's prescient insights into planetary geology, the Geological Society of America created the G.K. Gilbert Award for planetary geology in 1983. Gilbert's wide-ranging scientific ideas were so profound that the Geological Society of America published GSA Special Paper 183 on his research (Yochelson, E.L., editor, 1980, The Scientific Ideas of G.K. Gilbert, fourteen separate biographical chapters, 148 pages). Craters on the moon and on Mars are named in his honor, as is Mount Gilbert in Alaska, and another Mount Gilbert in California. Publications "Report on the geology of the Henry mountains (1877) "Lake Bonneville" US Geological Survey Monograph No. 1. 1890. 438 p. "The Moon's face: a study of the origin of its features". Bulletin of the Philosophical Society of Washington (January 1898). "The Underground Water of the