universal. _Glacial Sculpture._ Within the present generation sculpture by glaciers has received much attention and has involved a reconsideration of the ability of ice to erode which in turn involves a crystallization of views of the mechanics of moving ice. The evidence for glacier erosion has remained largely physiographic and rests on a study of land forms. In fact, the inadequacy of structural features or of river corrasion to account for flat-floored, steep-walled gorges, hanging valleys, and many lake basins, rather than a knowledge of the mechanics of ice has led to the present fairly general belief that glaciers are powerful agents of rock sculpture. The details of the process are not yet understood. Erosion by glaciers enters the arena of active discussion in 1862–63. The possibility had been suggested by Esmark (1827) and by Dana (1849) in the description of fiords and by Hind (1855) with reference to the origin of the Great Lakes. It appears full-fledged in Ramsay’s classic, which was published simultaneously in England and in America.[72] The argument runs as follows: There is a close association of ancient glaciers and lakes especially in mountains; glaciers are amply able to erode; evidences of faulting, special subsidence, river erosion, and marine erosion are absent from the lake basins of Switzerland and Great Britain. To quote Ramsay: “It required a solid body grinding steadily and powerfully in direct and heavy contact with and across the rocks to scoop out deep hollows, the situations of which might either be determined by unequal hardness of the rocks, by extra weight of ice in special places, or by accidental circumstances, the clue to which is lost from our inability perfectly to reconstruct the original forms of the glaciers.” “I believe with the Italian geologists, that all that the glaciers as a whole effected was only slightly to deepen these valleys and materially to modify their general outlines, and, further (a theory I am alone responsible for), to deepen them in parts more considerably when, from various causes, the grinding power of the ice was unusually powerful, especially where, as in the lowlands of Switzerland, the Miocene strata are comparatively soft.” Whittlesey (1864)[73] considered that the rock-bound lakes and narrow bays near Lake Superior were partly excavated by ice. LeConte (1875)[74] records some significant observations in a pioneer paper on glacier erosion which has not received adequate recognition. He says: “... I am convinced that a glacier, by its enormous pressure and resistless onward movement, is _constantly breaking off large blocks_ from its bed and bounding walls. Its erosion is not only a grinding and scoring, but also a _crushing and breaking_. It makes by its erosion not only rock-meal, but also large _rock-chips_.... Its erosion is a constant process of alternate _rough hewing_ and _planing_.