William Hittell Sherzer

“ In case the melting at the lower extremity, however, just equals the forward movement, the end of the glacier comes to a halt and its load is dumped in a ridge, forming a terminal moraine, providing we have a glacier of the alpine type, which alone can be considered to have an end. In the case of the three other types of glaciers such moraines, testifying to the stages of halt of the front, but not of the ice itself, are known as frontal moraines. ”

“ When a glacier of considerable thickness moves over a jointed, stratified rock, especially if the dip of the strata is in the direction of the movement, masses of rock may be detached bodily, giving rise to what is termed plucking. ”

“ When one portion of the mass begins to lag it may be thrust forward bodily by great pressure from behind, compelled to mount reverse slopes, to scour the bed, detach rock fragments and transport whatever material finds lodgment within or upon the mass. ”

“ Aside from the wind-blown dust which may be more or less evenly distributed throughout the body of the ice, the bulk of the material transported by the local ice-caps and continental ice-sheets lies in the basal layers. In the case of alpine and piedmont glaciers, however, from overtowering cliffs the active atmospheric agents may detach rock fragments which find their way to the surface of the glacier. ”

“ The eroding action of pure ice upon firm rock, varying in hardness from that of limestone to quartzite, is apparently slight and limited to a smoothing and polishing effect. When the glacier is shod with rock fragments, as is frequently the case, and has considerable thickness, the erosive effect may be great if the action is prolonged. ”

“ Occasionally rocky islands protrude through the frozen sea and are known as nunataks. If the supply of snow is sufficiently reduced the surface of the cap is slowly lowered, the marginal lobes are withdrawn and there may remain only the original piedmont and alpine glaciers from which the cap was developed. The field evidence is that all the existing group of glaciers in the Rockies and Selkirks were, in recent geological time, encased in such deposits of ice and snow, with only the higher peaks and ridges protruding. ”

“ The loose material which a glacier finds in its path, along with that which it is able to pluck from its bed, is urged forward by sliding and rolling, or it may be incorporated into the base of the ice and transported bodily. ”

“ The Horseshoe Glacier at the head of the neighboring Paradise Valley is of this same type, containing some sixteen alpine, component streams.
A similar although less characteristic type of piedmont glacier may originate upon an elevated mountain slope, which is crossed by a series of sub-parallel depressions, separated by rather low divides. Each depression may at first support a small alpine glacier, which, under favorable conditions for growth, may increase in thickness until it more than fills its bed and unites laterally with its neighbors. ”

“ Hard rocks are gouged, scratched and planed and the fragments reduced to pebbles, sand and clay. The glacier's rock tools by which this action is accomplished are bruised, battered, planed and scratched and the edges and corners are more or less rounded in a manner entirely characteristic of glaciers. ”

“ MORAINES, VICTORIA GLACIER, CANADIAN ROCKIES
The coarse character of the blocks and the lack of filling material are believed to have resulted from the loading of the ancient glacier by means of an earthquake shock.
of gravel, sand and clay, differing strikingly from the moraines formed previously and subsequently. Between the great blocks, many of enormous size, spaces permit the entrance of man and other animals, so that Professor Tarr's name of "bear-den moraine" seems appropriate. ”

“ EASTERN MARGIN OF THE ILLECILLEWAET LOCAL ICE-CAP, SELKIRKS, B.C.
Note the relatively even character of the surface of the cap and its freedom from crevasses and rock debris.
there is more or less of a horizontal component. The chief factors concerned are the configuration of the collecting area and the weight of the accumulated snow. If movement is not permitted the entire mass remains a snow bank, or heap of stagnant ice which does not possess the essential characteristics of a glacier. ”

“ Space does not permit the discussion here of the distribution of modern and ancient glaciers over the face of the earth by which the application of the above conditions might be more readily comprehended by the reader. ”

“ Material carried thus either upon or within the ice suffers little abrasion compared with that at the base, but by means of crevasses and moulins it may work its way down to the lower zone. The transporting power of a glacier differs very markedly from that of a river since it is in no wise dependant upon its velocity. Rocks as large as a city block may be handled quite as easily as a grain of sand.
Owing to its relation to the steep cliffs of the Ten Peaks the Wenkchemna receives rock fragments along its entire breadth. ”

“ They conform more or less perfectly to the shape of the valley and irregularities of the bed, move more rapidly towards the centre and upper surface than toward the sides and bottom, flow more rapidly down steep slopes than gentle ones, and are more active during the day than at night and in summer than in winter. ”

“ Glaciers like the Geikie, whose bounding cliffs extend in a northeast-southwest direction, i.e., in the direction of wave transmission, would be able to secure but a slight load and might reasonably be expected to show no such moraines. ”