On the Cause, Date, and Duration of the Last Glacial Epoch of Geology, and the Probable Antiquity of Man: With an Investigation and Description of a New Movement of the EarthChapman & Hall, 1873 - 288 páginas |
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On the Cause, Date, and Duration of the Last Glacial Epoch of Geology, and ... Alfred Wilks Drayson Sin vista previa disponible - 2015 |
Términos y frases comunes
altitude America angular distance annual appears arc joining arctic circle assumed astronomical boulder period calculation cause centre of polar century changes in latitude circle described circle round circle traced climatic changes cold consequently course traced curve decrease deposits direction drift earth earth's axis ecliptic effects eocene equinoxes Europe evidence examine explain facts formula geological geologists geometrical give given glacial epoch glaciers heat heavens Hevelius hitherto hours right ascension icebergs investigation known land longitude meridian miocene moraines mountains moved northern hemisphere objection obliquity obtain occur plane pliocene polar motion polar movement position precession present probably problem produce proper motion Ptolemy Ptolemy's catalogue regions relative remarks revolution right angles right ascension rocks rotation round the pole snow summer sun's supposed surface tertiary theory tion traced a circle tropics Tycho valleys variation varies its distance whilst winter
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Página 283 - Cold alone will not produce glaciers. You may have the bitterest north-east winds here in London throughout the winter, without a single flake of snow. Cold must have the fitting object to operate upon, and this object — the aqueous vapour of the air — is the direct product of heat.
Página 288 - For my own part, I cannot but think it exceedingly ridiculous to hear some men talk of the circumference of the earth, pretending, without the smallest .reason or probability, that the ocean encompasses the earth ; that the earth is round, as if mechanicafly formed so; and that Asia is equal to Europe.
Página 64 - ... will not (it seems to me) be admitted for a moment by any impartial observer. It has obviously been the result of different agencies and of different epochs ; the result of causes sometimes operating feebly and slowly, and at other times violently and powerfully.
Página 96 - The other great accumulation of erratic blocks seems due to some more general cause, since not only are the blocks scattered in great abundance over Northern Europe, in a manner to show their northern origin, but those which occur in the northern parts of America apparently in equal abundance, also point to a similar origin.* We hence infer that some cause, situated in the polar regions, has so acted as to produce this dispersion of solid matter over a certain portion of the earth's surface.
Página 277 - Astronomy," described the movement of the pole as describing a circle round the pole of the ecliptic as a centre and at a uniform distance from it of 23° 28'. though in another article he admitted a decrease of obliquity of 48...
Página 122 - It being a geometrical law that the obliquity of the ecliptic can be measured at any time by obtaining the angular distance between the pole of the heavens and the pole of the ecliptic...
Página 55 - Again, lavas and melted basalts cool, according to the size of the mass, at the rate of so many degrees in a given time : how many millions of years must have elapsed (supposing an original igneous condition of the earth) before its crust had attained a state of solidity ? or farther, before its surface had cooled down to the present mean temperature?
Página 55 - Many ingenious calculations have, no doubt, been made to approximate the dates of certain geological events, but these, it must be confessed, are more amusing than instructive. For example, so many lines of mud are annually laid down by the inundation of the Nile, fragments of pottery have been found at the depth of thirty feet. How many years...
Página 247 - That we must greatly extend our present chronology with respect to the first existence of man, appears inevitable ; but that we should count by hundreds of thousands of years is, I am convinced, in the present state of the inquiry, unsafe and premature.
Página 188 - ... is to say, the actual curve traced by the pole of the heavens relative to the pole of the ecliptic during 230 years does not differ one second from the circumference of a circle having a radius of 29° 25' 47", and its centre 6° from the pole of the ecliptic.