Cerenkov radiation
Cerenkov radiation The light emitted by charged particles such as protons or electrons when they pass through a transparent medium (e.g. the Earth's atmosphere, glass, or certain plastics) at a speed greater than the speed of light in that medium. The effect is the electromagnetic equivalent of a sonic boom. The radiation can occur at any wavelength, but increases in intensity with frequency and so is strongest in the blue and ultraviolet. The high-energy particles involved may be the secondary products of gamma rays or cosmic rays. For example, when gamma rays with energies of 10
12 eV pass through the Earth's atmosphere they generate secondary electrons, and ground-based optical telescopes can detect the flash of blue light they emit. Cerenkov radiation is named after the Russian physicist Pavel Alexeyevich Cerenkov (1904–90).
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A Geologic Time Scale 2004.(Book review)
Magazine article from: Geoscience Canada; 12/1/2006; ; 700+ words
; A Geologic Time Scale 2004 Edited by...complete answer ... the art of timescale construction lies in collaboration...as the detailed charts and tables. But this third edition...Methods (chapters 3-8), Geologic Periods (chapters 9-22...
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Substrate affinity and diversity dynamics of Paleozoic marine animals
Magazine article from: Paleobiology; 7/1/2006; ; 700+ words
; ...paleoenvironments seen in the geologic record is the Phanerozoic...other carbonates; see Table 1). Although some analyses...Within a given span of geologic time, animal taxa that...leads to the operational timescale of Table 2. Note that Sepkoski...
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The Treatment of Geological Time & the History of Life on Earth IN HIGH SCHOOL BIOLOGY TEXTBOOKS
Magazine article from: The American Biology Teacher; 9/1/2007; ; 700+ words
; ...but they lacked a clear chronology of geologic events. Similarly, Marques and Thompson...huge numbers involved in the geological timescale cause similar confusion among adults...school biology textbooks for this review (Table 1). All of these texts have publication...
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geologic timescale
Book article from: The Columbia Encyclopedia, Sixth Edition
...common is based on geologic time units, which...epochs. In some timescales, epochs are further...into ages. Each geologic time chart varies...are listed in the table entitled Geologic Timescale , see separate articles...
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Quaternary period
Book article from: The Columbia Encyclopedia, Sixth Edition
Quaternary period , younger of the two geologic periods of the Cenozoic era of geologic time (see Geologic Timescale , table) from 2 millon years ago to the present. Comprising all geologic time from the...
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Tertiary period
Book article from: The Columbia Encyclopedia, Sixth Edition
...of the Cenozoic era , the most recent of the geologic eras (see Geologic Timescale , table) from around 26 to 66 million years ago...Quaternary were, and still are, used, but other geologic literature substitutes other names, including...
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Carboniferous period
Book article from: The Columbia Encyclopedia, Sixth Edition
...period , fifth period of the Paleozoic era of geologic time (see Geologic Timescale , table), from 350 to 290 million years ago. Historical...Pennsylvanian; in the United States the break in the geologic sequence is so sharp that each division is...
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epoch
Book article from: The Columbia Encyclopedia, Sixth Edition
epoch unit of geologic time that is a subdivision of a period...also used to describe a short length of geologic time during a special occurrence, such as the glacial epoch. See geology ; Geologic Timescale (table).
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