منابع مشابه
Low atmospheric CO(2) levels during the Permo- Carboniferous glaciation inferred from fossil lycopsids.
Earth history was punctuated during the Permo-Carboniferous [300-250 million years (Myr) ago] by the longest and most severe glaciation of the entire Phanerozoic Eon. But significant uncertainty surrounds the concentration of CO(2) in the atmosphere through this time interval and therefore its role in the evolution of this major prePleistocene glaciation. Here, I derive 24 Late Paleozoic CO(2) ...
متن کاملImpacts, Tillites, and the Breakup of Gondwanaland
Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites <2...
متن کاملDid the breakout of laurentia turn gondwanaland inside-out?
Comparative geology suggests that the continents adjacent to northern, western, southern, and eastern Laurentia in the Late Proterozoic were Siberia, Australia-Antarctica, southern Africa, and Amazonia-Baltica, respectively. Late Proterozoic fragmentation of the supercontinent centered on Laurentia would then have been followed by rapid fan-like collapse of the (present) southern continents and...
متن کاملNeoproterozoic glaciation in the Earth System
The Neoproterozoic contains severe glacial intervals (750–580 Ma) including two extending to low palaeomagnetic latitudes. Paucity of radiometric dates indicates the need for chronostratigraphic tools. Whereas the marine Sr/Sr signatures show a steady rise, C fluctuates, the most reproducible variations being negative signatures in carbonate caps to glacial units, but more diagenetic work is ne...
متن کاملGlaciation as a migratory switch
Migratory behavior in birds is evolutionarily plastic, but it is unclear how this behavior responded during glacial cycles. One view is that at glacial maxima, species simply shifted their breeding ranges south of glacial ice and remained migratory. To test this hypothesis, we constructed ecological niche models for breeding and wintering ranges of 56 species, finding that 70% of currently long...
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ژورنال
عنوان ژورنال: Geological Magazine
سال: 1963
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800055400