NOAA caption: <a href="//commons.wikimedia.org/wiki/Clarence_Edward_Dutton" class="mw-redirect" title="Clarence Edward Dutton">Clarence Edward Dutton</a>, famous <a href="//commons.wikimedia.org/wiki/Geologist" class="mw-redirect" title="Geologist">geologist</a> of the late Nineteenth Century. An originator of the "Theory of Isostasy," an early seismologist, and the first to head the USGS division of volcanic geology. (1841-1912.)
photographer unknown -- property of US National Oceanic &amp; Atmospheric Administration
<a rel="nofollow" class="external free" href="http://www.photolib.noaa.gov/htmls/pers0069.htm">http://www.photolib.noaa.gov/htmls/pers0069.htm</a> -- NOAA's People Collection, Image ID pers0069