EDWARD HITCHCOCK AS EXEMPLAR AND EXCEPTION IN THE RECEPTION OF THE GLACIAL THEORY

Like the majority of American geologists of his generation, Edward Hitchcock (1793-1864) did not accept the glacial theory of Louis Agassiz; in particular, the notion of a continental ice sheet covering northern North America (and Europe). Despite being one of the first American geologists to investigate Agassiz's theory, and his initial display of enthusiasm regarding its explanatory powers, by 1842, Hitchcock back-pedaled into a conservative stance that merely argued for some combination of ice-and-water (which he labeled “glacio-aqueous” action) to explain the so-called ‘drift phenomena'. Nor did he accept any of the other leading theories (which included icebergs and the ‘wave of translation' of the Rogers brothers).

Instead, Hitchcock postulated a geologically recent submergence (and reemergence) of the North American continent, of more than 2,000 feet in vertical extent, which he felt could best explain the drift features, and especially the phenomena of valley terraces, which he outlined in his monograph, Illustrations of Surface Geology (1857). After seeing firsthand some of the glacial phenomena of Wales and Switzerland, he did come to acknowledge the presence of glacial striations upon some of the mountains in western Massachusetts and Vermont, but regarded these as isolated instances of alpine-type features. In spite of this (and other mounting) evidence that left his own hypothesis increasingly strained beyond credulity, Hitchcock never capitulated his position.

Hitchcock's seeming commitment to actualism, however, marks a significant departure from his earlier views as a ‘scriptural' geologist (during the 1820s and 1830s). Whether on methodological or evidential grounds, he eliminated (to his own satisfaction) all rival theories of the drift. His own inability to extrapolate from alpine to continental glaciation seemingly exemplifies much of the reluctance of American geologists to accept Agassiz's glacial theory (that is, before James Dwight Dana's gradual endorsement during the 1860s and 1870s).