12.—TheChallengerExpedition and Geology

Abstract

SynopsisIn exploring the results of the voyage of H.M.S. Challenger it is interesting to look at its impact on the science of geology. The expedition provided the first general picture of the topography and character of the sea bed, and though the actual working up of the results of this and of many subsequent voyages was done in Edinburgh by Murray and Renard, and there was no further development of marine geology as a speciality in this country at that stage, their work had an impact that far exceeded the confines of the group. This paper looks briefly at the development of two of the main ideas to arise from the Challenger studies and at their reception by the geological community in the United Kingdom.Murray and Renard (1884) concluded that their results pointed to the likelihood that ocean basins had occupied their present positions since early geological time. They based this idea on the differing character and slower rate of deposition of the deep ocean sediments as compared to the terrigenous sediments from which sedimentary strata on land are derived and which are deposited close to the shore. Other people produced evidence from different sources, pointing to the same conclusion but its validity was strongly debated by geologists holding the opposite point of view. Both sides were, however, hampered in developing their arguments by lack of understanding of the basic processes which had led to the differentiation of the continents and the oceans and which determine why mountain building should take place in one area and not in another.Controversy also surrounded Murray's theory of coral reefs. This too was partly associated with more fundamental issues since Darwin's theory which it was intended to supplant, though this did not happen as things turned out, was founded on the idea that general subsidence had taken place in the oceans, which would have been incompatible with the idea of permanence. Murray's theory was designed to account for the various coral formations without invoking subsidence.The Duke of Argyll was right in thinking that Murray's theory had not had the response for which he hoped, but the probable cause seems not to have been geologists' undue reverence for Darwin's pronouncements, as he supposed, though this may have been a minor factor in the situation, but rather the able defence of his theory by Dana and others, and the fact that geologists, while alive to the need for their science to provide an explanation of the basic earth processes, were unable to find a paradigm within which they could work. In its absence they had no framework to suggest answers to these individual questions or to indicate fruitful lines of enquiry to pursue for their solution. They tended therefore to continue working along accustomed lines and, unless well established in traditional areas, to avoid involvement in tangential issues. In spite of the support which they received from Archibald Geikie, neither of these ideas, permanence of ocean basins or the formation of coral reefs without recourse to subsidence, ever came to enjoy anything like universal assent, though both appear as accepted points of view in scientific and general works published at and after the turn of the century.