Features Resulting From Glaciation
The Problem Stated
Early in the nineteenth century when speculation regarding the interior of the earth gave place in part to observations of the surface of the earth, geologists were confronted with perhaps the most difficult problem in the history of the science. As stated by the editor of the Journal in 1821:32
“The almost universal existence of rolled pebbles, and boulders of rock, not only on the margin of the oceans, seas, lakes, and rivers; but their existence, often in enormous quantities, in situations quite removed from large waters; inland,—in high banks, embedded in strata, or scattered, occasionally, in profusion, on the face of almost every region, and sometimes on the tops and declivities of mountains, as well as in the vallies between them; their entire difference, in many cases, from the rocks in the country where they lie—rounded masses and pebbles of primitive rocks being deposited in secondary and alluvial regions, and vice versa; these and a multitude of similar facts have ever struck us as being among the most interesting of geological occurrences, and as being very inadequately accounted for by existing theories.”
The phenomena demanding explanation—jumbled masses of “diluvium,” polished and striated rock, bowlders distributed with apparent disregard of topography—were indeed startling. Even Lyell, the great exponent of uniformitarianism, appears to have lost faith in his theories when confronted with facts for which known causes seemed inadequate. The interest aroused is attested by 31 titles in the Journal during its first two decades, articles which include speculations unsupported by logic or fact, field observation unaccompanied by explanation, field observation with fantastic explanation, ex-cathedra pronouncements by prominent men, sound reasoning from insufficient data, and unclouded recognition of cause and effect by both obscure and prominent men. With little knowledge of glaciers, areal geology, or of structure and composition of drift, all known forces were called in: normal weathering, catastrophic floods, ocean currents, waves, icebergs, glaciers, wind, and even depositions from a primordial atmosphere (Chabier, 1823). Human agencies were not discarded. Speaking of a granite bowlder at North Salem, New York, described by Cornelius (1820)33 as resting on limestone, Finch (1824)34 says: “it is a magnificent cromlech and the most ancient and venerable monument which America possesses.” In the absence of a known cause, catastrophic agencies seem reasonable.