Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Arctic East Siberia had a lower latitude in the Pleistocene   In Arctic East Siberia many remains of mammoths have been found. In this
region there is not sufficient sunlight over the year to allow for the growth
of the plants on which these animals feed. Consequently the latitude of these
regions must have been lower before the end of the Pleistocene than at present.
It is a challenge to reconstruct this geographic shift of the poles in a manner
compa- tible with known facts. A possible sequence of events is described here.
It as- sumes an additional planet, which must since have disappeared. This is
possible, if it moved in an extremely eccentric orbit and was hot as a result
of tidal work and solar radiation. During a few million years evaporation of
this planet led to a disk-shaped cloud of ions moving around the Sun. This
cloud partially shielded the Earth from the solar radiation, producing the
alteration of cold and warm periods characterizing the Pleistocene. The degree
of shielding is sensitive to the inclination of Earth's orbit, which has a
period of 100000 years. Two cloud structures are discussed. The first is small
and steady. The other builds up to a point where inelastic collisions between
particles induce its collapse The resulting near-periodic time dependence of
the shielding re- sembles that of Dansgaard-Oeschger events. The Pleistocene
came to an end when the additional planet had a close encounter with the Earth,
whereby the Earth suffered a one permil extensional deformation. While this
deformation relaxed to an equilibrium shape in a time of one to several years,
the globe turned relative to the rotation axis: The North Pole moved from
Greenland to the Arctic Sea. The additional planet split into fragments, which
subsequently evaporated. Simple estimates are used here for the
characterization of the complex processes; more elaborate studies are required.

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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: q-alg