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.Comment: 10 pages, LaTex, Typing error corrected in list of author

Cosmic ray records in Antarctic meteorites

The cosmogenic radionuclides Be(10), Al(26), and Mn(53) and noble gases were determined in more than 28 meteorites from Antarctica by nuclear analytical techniques and static mass spectrometry, respectively. The summarized results are listed. The concentrations of Al(26) and Mn(53) are normalized to the repective main target elements and given in dpm/kg Si sub eq and dpm/kg Fe. The errors stated include statistical as well as systematical errors. For noble gas concentrations estimated errors are 5% and for isotopic ratios 1.5%. Cosmic ray exposure ages T sub 21 were calculated by the noble gas concentrations and the terrestrial residence time (T) on the basis of the spallogenic nuclide Al(26). The suggested pairing of the LL6 chondrite RKPA 80238 and RKPA 80248 and the eucrites ALHA 76005 and ALHA 79017 is confirmed not only by the noble gas data but also by the concentrations of the spallation produced radionuclides. Futhermore, ALHA 80122, clasified as an H6 chondrite, has a noble gas pattern which suggest that this meteorite belongs to the ALHA 80111 shower