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87:6673 How hot is the heart of the Earth?
1012
F. General
chemical processes to explain the Antarctic ozone deficit, chlorine (a byproduct of chlorofluorocarbon use) is now implicated as being at least partially responsible. These findings suggest that 'nonstandard chemistry' is at work, and that Antarctic atmospheric models will need adjustment. (wbg) 87:6670
Peddy, Carolyn and Charlotte Keen, 1987. Deep seismic reflection profiling: how far have we come? Leading Edge, 6(6):22-24, 49. New deep-reflection data presented at the Second International Symposium on Deep Seismic Reflection Profiling of the Continental Lithosphere (Cambridge, England, July 15-17, 1986) have resulted in major changes in fundamental concepts in crustal dynamics. Six large consortia based in North America, Europe, and Australia--COCORP, BIRPS, LITHOPROBE, ECORS, ACORP, and D E K O R P ~ h a v e produced profiles across mountain belts, continental margins, and subduction zones which reveal new details on the processes involved in collisions, faulting, and subduction and on the nature of the Moho. BIRPS, Bullard Lab., Cambridge, UK. (hbf) 87:6671
Raup, D.M., 1987. Mass extinction: a commentary. Palaeontology, 30(1): 1-13. The revival of catastrophism as a concept to which geologists might refer centers on four present claims often, but not by necessity, made in combination: (1) the Cretaceous boundary extinction was caused by a collision, (2) other mass extinctions are collisionrelated, (3) extinction events are periodic, (4) impact events are periodic. These claims are discussed in light of the evidence for them, and an appeal is made to more carefully consider other possible extraterrestrial effects on Earth's long history. Dept. of Geophysical Sci., Univ. of Chicago, IL 60637, USA. (fcs) 87:6672
Weisburd, S., 1987. Volcanoes and extinctions: round two. Sci. News, Washington, D.C., 131(16):248250. Although Walter Alvarez and other champions of the impact theory of extinctions at the K - T boundary disagree, others such as Vincent E. Courtillot and Charles Officer believe the volcanic theory is still viable. Evidence they cite are a more precise date of ~ 6 6 m.y. for the Deccan Traps, new evidence for worldwide distribution of magma from volcanic eruptions, iridium levels at Kilauea, shocked-mineral findings, and other links between extinctions and volcanoes. (lit)
OLR (1987)34(11)
87:6673 Weisburd, S., 1987. How hot is the heart of the Earth? Sci. News, Washington, D.C., 131(16):p.245. Technical advances have enabled researchers to experimentally determine the melting point of iron, the dominant material of the Earth's core, at pressures approximating those at the center of the Earth. Results indicate that the melting point of iron at the 136 GPa pressure of the core-mantle boundary is 4800_+ 200 K and is 7600_+ 500K at the 330 GPa pressure of the solid-inner/liquid-outer core boundary. The presence of other elements would lower the melting point by ~1000 K, making the temperature at the top of the core 3800 K or 1000 K higher than the calculated temperature at the base of the mantle, implying the presence of a nonconvecting layer in the mantle to prevent rapid heat escape from the core. The best estimate for the temperature of the solid inner core itself is not more than 6900_+ 1000 K. (hbf) 87:6674
White, R.S., 1987. When continents rift. [Report.] Nature, Lond., 327(6119):p.191. A London conference (March 1987) treating 'Early Tertiary volcanism and the opening of the northeast Atlantic,' has served to emphasize the enormous amount of volcanic activity which accompanied the rifting of Greenland from Europe and created the Tertiary igneous province of Greenland, the Faroes, northwest Scotland, and Ireland. It is estimated that 5-10 × 106 km 3 of igneous rock were generated, the bulk forming in a relatively brief 2-3 m.y. time span. The exact position of the continent-ocean boundary during this interval and the cause of the intense, rapid igneous activity remain matters of controversy. Dept. of Earth Sci., Bullard Lab., Univ. of Cambridge, CB3 0EZ, UK. (hbf)
F390. Educational literature 87:6675 Ellis, Richard, 1987. Why do whales strand? Oceans, 20(3):24-29, 63. Though we have known about whale strandings for at least 2300 years (when Aristotle referred to them), we still do not know why they run aground. Theories abound: navigational system impairment, escape from predators, sloping beaches which prevent warning by echolocation, attempts to avoid drowning during stress (a theory which the author likes), and even by intent. But disconfirming evidence, discussed here, is also abundant. Despite witnessing
F. General
chemical processes to explain the Antarctic ozone deficit, chlorine (a byproduct of chlorofluorocarbon use) is now implicated as being at least partially responsible. These findings suggest that 'nonstandard chemistry' is at work, and that Antarctic atmospheric models will need adjustment. (wbg) 87:6670
Peddy, Carolyn and Charlotte Keen, 1987. Deep seismic reflection profiling: how far have we come? Leading Edge, 6(6):22-24, 49. New deep-reflection data presented at the Second International Symposium on Deep Seismic Reflection Profiling of the Continental Lithosphere (Cambridge, England, July 15-17, 1986) have resulted in major changes in fundamental concepts in crustal dynamics. Six large consortia based in North America, Europe, and Australia--COCORP, BIRPS, LITHOPROBE, ECORS, ACORP, and D E K O R P ~ h a v e produced profiles across mountain belts, continental margins, and subduction zones which reveal new details on the processes involved in collisions, faulting, and subduction and on the nature of the Moho. BIRPS, Bullard Lab., Cambridge, UK. (hbf) 87:6671
Raup, D.M., 1987. Mass extinction: a commentary. Palaeontology, 30(1): 1-13. The revival of catastrophism as a concept to which geologists might refer centers on four present claims often, but not by necessity, made in combination: (1) the Cretaceous boundary extinction was caused by a collision, (2) other mass extinctions are collisionrelated, (3) extinction events are periodic, (4) impact events are periodic. These claims are discussed in light of the evidence for them, and an appeal is made to more carefully consider other possible extraterrestrial effects on Earth's long history. Dept. of Geophysical Sci., Univ. of Chicago, IL 60637, USA. (fcs) 87:6672
Weisburd, S., 1987. Volcanoes and extinctions: round two. Sci. News, Washington, D.C., 131(16):248250. Although Walter Alvarez and other champions of the impact theory of extinctions at the K - T boundary disagree, others such as Vincent E. Courtillot and Charles Officer believe the volcanic theory is still viable. Evidence they cite are a more precise date of ~ 6 6 m.y. for the Deccan Traps, new evidence for worldwide distribution of magma from volcanic eruptions, iridium levels at Kilauea, shocked-mineral findings, and other links between extinctions and volcanoes. (lit)
OLR (1987)34(11)
87:6673 Weisburd, S., 1987. How hot is the heart of the Earth? Sci. News, Washington, D.C., 131(16):p.245. Technical advances have enabled researchers to experimentally determine the melting point of iron, the dominant material of the Earth's core, at pressures approximating those at the center of the Earth. Results indicate that the melting point of iron at the 136 GPa pressure of the core-mantle boundary is 4800_+ 200 K and is 7600_+ 500K at the 330 GPa pressure of the solid-inner/liquid-outer core boundary. The presence of other elements would lower the melting point by ~1000 K, making the temperature at the top of the core 3800 K or 1000 K higher than the calculated temperature at the base of the mantle, implying the presence of a nonconvecting layer in the mantle to prevent rapid heat escape from the core. The best estimate for the temperature of the solid inner core itself is not more than 6900_+ 1000 K. (hbf) 87:6674
White, R.S., 1987. When continents rift. [Report.] Nature, Lond., 327(6119):p.191. A London conference (March 1987) treating 'Early Tertiary volcanism and the opening of the northeast Atlantic,' has served to emphasize the enormous amount of volcanic activity which accompanied the rifting of Greenland from Europe and created the Tertiary igneous province of Greenland, the Faroes, northwest Scotland, and Ireland. It is estimated that 5-10 × 106 km 3 of igneous rock were generated, the bulk forming in a relatively brief 2-3 m.y. time span. The exact position of the continent-ocean boundary during this interval and the cause of the intense, rapid igneous activity remain matters of controversy. Dept. of Earth Sci., Bullard Lab., Univ. of Cambridge, CB3 0EZ, UK. (hbf)
F390. Educational literature 87:6675 Ellis, Richard, 1987. Why do whales strand? Oceans, 20(3):24-29, 63. Though we have known about whale strandings for at least 2300 years (when Aristotle referred to them), we still do not know why they run aground. Theories abound: navigational system impairment, escape from predators, sloping beaches which prevent warning by echolocation, attempts to avoid drowning during stress (a theory which the author likes), and even by intent. But disconfirming evidence, discussed here, is also abundant. Despite witnessing