摘要:

Examples of heliotropism are easily observed in the microbially produced stromatolitic columnar growths in the thermal effluents from geysers and hot springs at Yellowstone National Park, Wyo. Six effluent regions with microbial mats that produce centimeter‐sized conical to columnar structures have been analyzed. The columns or cones tilt south at up to 30° zenith angles, independent of water flow direction (velocities up to 8 cm/s). Subsurface layers and shallow cores of siliceous sinter, presumably microbially produced, also appear to preserve evidence of earlier heliotropism. In combination with similar discoveries in living stromatolitic structures at Shark Bay, Western Australia, this evidence provides a foundation upon which a methodology can be developed for using selected ancient stromatolites to deduce paleo‐latitude, paleo‐obliquity of the ecliptic, paleo‐days per month and year (by using laminae counts), paleo—spin axis north‐south, paleolocation of the geomagnetic pole (using paleomagnetism), and other paleoearth and earth‐sun

ISSN:0002-8606    

DOI:10.1029/EO067i013p00153

年代:1986

数据来源: WILEY

摘要:

A long‐standing problem in measuring the terrestrial heat flow beneath the ocean floors has been the acquisition of deep temperature information comparable to that more readily obtained on the continents. While rather sophisticated sediment temperature and in situ thermal conductivity probes have evolved over the years from the simplicity of the Bullard and Ewing designs [Langseth, 1965;Lister, 1979;Hyndman et al., 1979], they are limited to a few meters of penetration. The improved accuracy and detail afforded by these later designs have revealed dynamic phenomena that are crucial to an understanding of processes in the ocean lithosphere [e.g.,Anderson et al., 1979;Langseth and Herman, 1981] and that can best be studied in deep holes over an extended period of time. Recently, a prototype system has been installed in an offshore petroleum exploration well in the Canadian Arctic to demonstrate the technology of measuring precise wellbore temperatures to hundreds of meters depth at frequent intervals over a period of several year

ISSN:0002-8606    

DOI:10.1029/EO067i013p00154

年代:1986

数据来源: WILEY

摘要:

In order to understand the physical, chemical, and biological processes that regulate the earth's environment—the environment that allows life to flourish—a program must be undertaken in which “scientific disciplines forsake their accustomed imperatives and serve as tools rather than ends in themselves,” according to a recent report from the U.S. Committee for an International Geosphere‐Biosphere Program (IGBP). This National Research Council (NRC) committee made recommendations for initial priorities for a program to study “global change in the geosphere‐biosphere.”The committee recommended that an IGBP should emphasize studies in three types of areas: those that seem most likely to explain interactions that might lead to significant change in the next 100 yr, those that most affect the biosphere, and those that are most susceptible to human perturbation. In their report, entitled “Global Change in the Geosphere‐Biosphere: Initial Priorities for an IGBP,” they laid out a framework for a program beginning in the 1990s and continuing “well beyond the dawn of the next century.” They recommended that a series of international workshops be held over the next 2 yr (possibly organized by the International Council of Scientific Unions) so that experts can make plans in g

ISSN:0002-8606    

DOI:10.1029/EO067i013p00157-01

年代:1986

数据来源: WILEY

摘要:

Within the last 20 years, the Rio Grande rift has been recognized as one of the major active rift zones of the world. As such, this feature has received increased attention by an international community of scientists (see, for example, the collections of papers edited byRiecker[1979] andPalmason[1982], as well as the journalTectonophysics, vol. 94, issues 1–4, 1983). The book reviewed here represents the latest and among the finest sets of papers describing current research on a fundamental element in the tectonic fabric of North Americ

ISSN:0002-8606    

DOI:10.1029/EO067i013p00158

年代:1986

数据来源: WILEY

摘要:

The recipients of the 1986 Bowie, Ewing, and Horton Medals and the Smith and Macelwane Awards have been announced by AGU. These distinctive honors recognize AGU members who make significant contributions to geophysics.The William Bowie Medal is awarded to James Dooge of University College, Dublin, Ireland, for outstanding contributions to fundamental geophysics and for unselfish cooperation in research. The Maurice Ewing Award will be presented to John Imbrie of Brown University, Providence, R.I. This honor is awarded for significant original contributions to understanding physical, geophysical, and geological processes in the ocean and/or outstanding service to marine sciences. The medal is presented jointly by the U.S. Navy and AGU.

ISSN:0002-8606    

DOI:10.1029/EO067i013p00161

年代:1986

数据来源: WILEY

摘要:

Perhaps the most striking broad implication of what we have learned from the data that have been returned from planetary missions is that planetary processes are diverse and complex. Scientists are challenged to extend the dynamic range of their models and theories and are often forced to recognize that each planet or satellite is special. Nevertheless, the principles of physics are common to all these objects, and the emerging outcome of this challenge is a better understanding of how planets work and a better appreciation of the earth as a planet. The comparative approach to planets, although sometimes frustrating, is invaluable and was the focus of a meeting held at the California Institute of Technology (Caltech), Pasadena, June 5–7, 198

ISSN:0002-8606    

DOI:10.1029/EO067i013p00163-01

年代:1986

数据来源: WILEY