|
1. |
The thermal and dynamic state of the Earth |
|
Eos, Transactions American Geophysical Union,
Volume 62,
Issue 31,
1981,
Page 609-612
Glyn M. Jones,
Preview
|
PDF (1990KB)
|
|
摘要:
The thermal state of the earth's interior is a topic of fundamental importance in many branches of geophysics. Investigations ranging from the dynamo theory of the origin of the earth's magnetic field to the driving mechanism for plate motions are all ultimately concerned with the question of how heat is transferred in various regions of the earth and what are the resulting flow patterns and temperature at depth.Present ideas on this problem are in a state of flux. New insights are being brought to bear on old problems, and additional questions are being raised. For example, analysis of postglacial rebound data from the Canadian shield has led to the interpretation that the effective viscosity of the lower mantle may not be significantly larger than that of the upper mantle, as had been previously thought. As a consequence, there has been a revival of interest in mantle‐wide convection as the dominant mode of heat transfer within the mantle. A major uncertainty which remains, however, is whether mantle‐wide convection would consist of a single flow system extending from the base of the lithosphere to the core‐mantle boundary or whether there are, for example, separate flow systems in the upper and lower mantle, separated by a thermal boundary layer at about the depth of the 670‐km phase tra
ISSN:0002-8606
DOI:10.1029/EO062i031p00609
年代:1981
数据来源: WILEY
|
2. |
Environmental cancer risks |
|
Eos, Transactions American Geophysical Union,
Volume 62,
Issue 31,
1981,
Page 612-612
Peter M. Bell,
Preview
|
PDF (140KB)
|
|
摘要:
In a long‐awaited report (‘Assessment of Technologies for Determining Cancer Risks From the Environment’), the U.S. Office of Technology Assessment (OTA) has evaluated the role of environmental factors in cancer diseases. Environment is interpreted broadly as encompassing anything that interacts with humans, including the natural environment, food, radiation, the workplace, etc. Geologic factors range from geographic location to radiation and specific minerals. The report, however, is based on an inadequate data base in most instances, and its major recommendations are related to the establishment of a national cancer registry to record cancer statistics, as is done for many other diseases. Presently, hard statistics are lacking in the establishment of some association between the cause‐effect relationship of most environmental factors and most carcinogens. Of particular interest, but unfortunately based on unreliable data, are the effects of mineral substances such as ‘asbestos.’ USGS mineralogist Malcolm Ross will review asbestos and its effects on human health in the forthcoming Mineralogical Society of America's Short Course on the Amphiboles (Reviews in Mineralogy, 9, in p
ISSN:0002-8606
DOI:10.1029/EO062i031p00612-01
年代:1981
数据来源: WILEY
|
|