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Updated: May 18, 2025
The considerable amount of vertical movement in opposite directions, which was suggested in the last chapter, as affording the most probable explanation of the position of some of the stratified and fossiliferous drifts of Scotland, formed since the commencement of the glacial period, will appear less startling if it can be shown that independent observations lead us to infer that a geographical revolution of still greater magnitude accompanied the successive phases of glaciation through which the Welsh mountains have passed.
Their characteristic form is that of a long, deep, narrow bay with steep rock walls and basined floor. Fjords are found only in regions which have suffered glaciation, such as Norway and Alaska. HANGING VALLEYS. These are lateral valleys which open on their main valley some distance above its floor.
Trimmer to have had a submarine origin, and Mr. Professor Ramsay, in a paper read to the Geological Society in 1851, and in a later work on the glaciation of North Wales, described three successive glacial periods, during the first of which the land was much higher than it now is, and the quantity of ice excessive; secondly, a period of submergence when the land was 2300 feet lower than at present, and when the higher mountain tops only stood out of the sea as a cluster of low islands, which nevertheless were covered with snow; and lastly, a third period when the marine boulder drift formed in the middle period was ploughed out of the larger valleys by a second set of glaciers, smaller than those of the first period.
Wright was originally introduced to the Expedition by Griffith Taylor, and Scott, advised by Wilson, was so keen on the inclusion of this young Canadian chemist in our scientific staff that really the study of ice structure and glaciation was made for Wright and his science coined for him.
He's doping out something right now that would fit you like a glove and say, it would be a great idea to kind a' specialize in that spur act of yours. That got over big. We could work it in again. An act like that's good for a million laughs." Mr. Armytage eyed Mr. Walberg coldly. Even Mr. Walberg felt an extensive area of glaciation setting in.
I considered that our own present vegetation, or its proximate ancestry, must have occupied the arctic and subarctic regions in pliocene times, and that it had been gradually pushed southward as the temperature lowered and the glaciation advanced, even beyond its present habitation; that plants of the same stock and kindred, probably ranging round the arctic zone as the present arctic species do, made their forced migration southward upon widely different longitudes, and receded more or less as the climate grew warmer; that the general difference of climate which marks the eastern and the western sides of the continents the one extreme, the other mean was doubtless even then established, so that the same species and the same sorts of species would be likely to secure and retain foothold in the similar climates of Japan and the Atlantic United States, but not in intermediate regions of different distribution of heat and moisture; so that different species of the same genus, as in Torreya, or different genera of the same group, as redwood, Taxodium, and Glyptostrobus, or different associations of forest-trees, might establish themselves each in the region best suited to the particular requirements, while they would fail to do so in any other.
Had the glacial epoch been long, as the earth counts time, these mountains would have been worn low by ice; had the epoch been remote, the marks of glaciation would already have been largely destroyed by other agencies.
It is admitted on all hands that they were once filled with ice, and as the existing glaciers polish and grind down, as before stated, the surface of the rocks, we are prepared to find that every lake-basin in countries once covered by ice should bear the marks of superficial glaciation, and also that the ice during its advance and retreat should have left behind it much transported matter as well as some evidence of its having enlarged the pre-existing cavity.
The brown silt loam prairie soil of the early Wisconsin glaciation is the most common type of the greatest soil area in the Illinois Corn Belt. Two million pounds of this surface soil contain as an average: Potassium 36,250 pounds Magnesium 8,790 pounds Calcium 11,450 pounds Phosphorus 1,190 pounds
Manifestly, they would have flocked, first to the Gulf states, then to Mexico, and afterwards to the Central American states; but none of them could ever have been crowded through the Isthmus of Panama, since at the height of the last glaciation, that portion of the continent must have been the tropical barrier to our northern forms, as it is now the equatorial barrier.
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