AT VULCANS SHOULDER - DANA,JAMES,DWIGHT AND THE BEGINNINGS OF PLANETARY VOLCANOLOGY

J. D. Dana was a pioneering American naturalist who put an impressive stamp on four fields-mineralogy, zoology, volcanology, and geology-dur ing a long career. Educated at Yale,the seminal event of his post-grad uate education was participation in the United States Exploring Expedi tion in the Pacific between 1838 and 1842. Observations of atolls, vol canic islands, and active Hawaiian volcanoes, together with insights g ained from the charting activities of the expedition, enabled him to m ake the first synthesis of volcanic action in the Pacific and to formu late the broader doctrines of the contrasts between, and the permanenc e of, continents and ocean basins, and of the historicity of the Earth . The magnitude of Dana's contribution must be viewed from the perspec tive of geological sciences in the early 19th century. At the onset of the Exploring Expedition, direct accounts of volcanic action were sca nt, the Wernerian neptunist view of the aqueous origin of basalt had o nly just been laid to rest, most geologists still had no clear concept ion of how basalts erupted from volcanoes, fossil sequences were only beginning to be understood, and both geological mapping and systematic stratigraphy were in their infancy. Dana had little formal training i n geology, but his observational skills were already evident in an ear ly description of flowing lava and fire fountaining at Vesuvius (1835) . Wide reading had made him familiar with current concepts of continen tal geologists. Dana was perhaps the first trained naturalist to obser ve the fluidal character of erupting basaltic lava, this at Kilauea on Hawaii, and he at once understood how this contrasted with the more v iscid attributes of lava at Vesuvius. But he was also able to perceive how basaltic eruptions could build a large volcanic island, and to un derstand that fluvial action and subsidence eventually could reduce a Hawaii to an eroded volcanic stub, sustained as a land area only by th e countergrowth of hinging and barrier reefs. Dana identified the line ar arrangements of volcanic chains on the sea floor and established th eir age progressions using extent of erosion and development of offsho re reefs. He predicted the existence of the vast tracts of drowned and deeply submerged atolls, now termed guyots, in the western Pacific, a nd said where they could be found. Dana the geologist was unreservedly historical, a perspective that reflected his Christian opinion of the human estate as the culmination of Divine creation. The geological pa st was directed toward this moment no less than recorded human history , with a genuine beginning and substantive changes through time. This view contrasted with the uniformitarian (deistic) opinions of Hutton a nd especially Lyell, who saw processes repeated through an indetermina nt length of time gth but no pattern of fundamental change. Dana's Nor th American puritan tradition gave him the optimism that an Earth hist ory could be established by human ingenuity and effort, and it persuad ed him to devote all his energies to this end. Dana entered the Pacifi c seeking broad patterns. The first of these he discerned was the inte raction of volcanic action, fluvial erosion, subsidence, and coral gro wth on the islands he explored, leading to formation of atolls. This p rovided proof of direction in Earth history and a unifying planetary p erspective, focused on volcanology, which was first outlined in Dana's report on Geology for the Exploring Expedition in 1849. Later, throug h voluminous writing and years of teaching, Dana carried these views t o a position of extraordinary influence and importance for all subsequ ent geological science.