Discussions on Climate and Cosmology

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A. & C. Black, 1885 - 327 páginas
 

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Página 52 - Were it not for the ice, the summers of North Greenland, owing to the continuance of the sun above the horizon, would be as warm as those of England ; but, instead of this, tho » Tyndall, " On Heat,
Página 286 - In the same way as the distances between the different planetary systems are not calculated by miles but by Sirius-distances, each of which comprises millions of miles, so the organic history of the earth must not be calculated by thousands of years, but by palaeontological or geological periods, each of which comprises many thousands of years, and perhaps millions, or even milliards, of thousands of years.
Página 271 - ... removed from the general surface in one year ; and there seems no danger of our overrating the mean rate of waste by selecting the Mississippi as our example, for that river drains a country equal to more than half the continent of Europe, extends through twenty degrees of latitude, and therefore through regions enjoying a great variety of climate, and some of its tributaries descend from mountains of great height. The Mississippi is also more likely to afford us a fair test of ordinary denudation,...
Página 178 - Sannikow found the skulls and bones of horses, buffaloes, oxen, and sheep in such abundance that these animals must formerly have lived there in large herds. At present, however, the icy wilderness produces nothing that could afford them nourishment, nor would they be able to endure the climate. Sannikow concludes that a milder climate must formerly have prevailed here, and that these animals may therefore have been contemporary with the mammoth, whose remains are found in every part of the island."...
Página 48 - ... thus radiated being of the same quality as that which the snow itself radiates is on this account absorbed by the snow. Little or none of it is reflected like that received from the sun. The consequence is that the heat thus absorbed accumulates in the snow till melting takes place. Were the amount of aqueous vapour possessed by the atmosphere sufficiently diminished, perpetual snow would cover our globe down to the sea-shore. It is true that the air is warmer at the lower than at the higher...
Página 157 - Whenever the area became wanner, the descendants of semi-tropical forms would gradually creep further and further north, whilst the descendants of cold-loving plants would retreat from the advancing temperature, vice versd. Whenever the area became gradually colder, the heat-loving plants would, from one generation to another, retreat further and further south, whilst the cold-loving plants would return to the area from which their ancestors had been driven out. In each case there would be some lingering...
Página 175 - These are," says Mr. Howorth, " found even more abundantly on the banks of the very short rivers east of the Lena. They are found not only on the deltas of these rivers, but far away to the north, in the islands of New Siberia, beyond the reach of the currents of the small rivers, whose mouths are opposite those islands." But a more convincing proof is that " they are found not only in North Central Siberia, where the main arteries of the country flow, but in great numbers east of the river Lena,...
Página 157 - Stenocarpus, and plants of the pea tribe, together with many others. The question which presents itself to one's mind, he remarks, is, how is it possible that the tropical forms, such as the palms, aroids, cactus, &c., could have grown alongside of the apparently temperate forms, such as the oak, elm, beech, and others ? Mr. Gardner's explanation is as follows : — " Astronomers, having calculated the path of the revolution of the earth in ages past, tell us that in recurring periods each hemisphere,...
Página 180 - The evidence, then," says Mr. Howorth, " of the ddbris of vegetation, and of the freshwater- and land-shells found with the Mammoth-remains, amply confirms the a priori conclusion that the climate of Northern Siberia was at the epoch of the Mammoth much more temperate than now. It seems that the botanical facies of the district was not unlike that of Southern Siberia, that the larch, the willow, and the Alnaster were probably the prevailing trees, that the limit of woods extended far to the north...
Página 178 - where the lakes on the tundra have grown small and shallow, we find on and near their banks a layer of turf, under which, in many places, are remains of trees in good condition, which support the other proofs that the northern limit of trees has retrogressed, and that the climate here has grown colder. I found, on the way from Dudino to the Ural Mountains, in a place where larches now only grow in sheltered rivervalleys, in turf on the top of the tundra, prostrate larch trees still bearing cones...

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