Publications
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Crustal structure of Oaxaca, Mexico, from seismic refraction measurements Crustal structure of Oaxaca, Mexico, from seismic refraction measurements
Seismic refraction and gravity data have been analyzed to obtain a model of the compressional-wave velocity structure of the ocean-to-continent transition in the State of Oaxaca in southwestern Mexico. Crustal thickness on the continent at the latitude 18°N is 45 ± 4 km, based on reflected phases from the Moho discontinuity. The crust has been modeled with three layers, with velocities...
Authors
C.M. Valdes, Walter D. Mooney, S.K. Singh, C. Lomnitz, James H. Luetgert, C.E. Helsley, B.T.R. Lewis, M. Mena
Stratigraphic potential of Bolboforma significantly increased by new finds in the North Atlantic and South Pacific Stratigraphic potential of Bolboforma significantly increased by new finds in the North Atlantic and South Pacific
Until now, the genus Bolboforma, a problematic group of calcareous microfossils, has been recorded only in Oligocene to Pliocene marine sedimentary rocks, chiefly in the eastern North Atlantic region. We add to this eastern North Atlantic record six new sites and eleven undescribed species from the continental slopes of Ireland and Morocco. More significantly, we record, for the first...
Authors
C. Wylie Poag, A. L. Karowe
Volcano monitoring at the U.S. Geological Survey's Hawaiian Volcano Observatory Volcano monitoring at the U.S. Geological Survey's Hawaiian Volcano Observatory
The island of Hawaii has one of the youngest landscapes on Earth, formed by frequent addition of new lava to its surface. Because Hawaiian are generally nonexplosive and easily accessible, the island has long attracted geologists interested in studying the extraordinary power of volcanic eruptions. The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO), now nearing its 75th...
Authors
Christina C. Heliker, J. D. Griggs, T. Jane Takahashi, Thomas L. Wright
Multispectral digital image mapping of Antarctic ice features Multispectral digital image mapping of Antarctic ice features
Landsat multispectral images of the Antarctic ice sheet have been digitally enhanced by the US Geological Survey to show ice surface features not seen in earlier photographic products of the same scenes. Now for the first time it is worthwhile to prepare image maps at scales of up to 1:250 000 of ice sheet areas even where no nunataks are visible. Derivatives of the data can be stretched...
Authors
Charles Swithinbank, Baerbel K. Lucchitta
Geophysics: A reversal of geomagnetic polarity Geophysics: A reversal of geomagnetic polarity
The detailed behaviour of the geomagnetic field during reversals is documented by palaeomagnetists to constrain models of the geomagnetic dynamo. Reversals are studied by measuring the magnetic remanence preserved in rocks to obtain both the direction and intensity of the ancient magnetic field.
Authors
Edward A. Mankinen
A note on the relationships between organic matter and some geotechnical properties of a marine sediment A note on the relationships between organic matter and some geotechnical properties of a marine sediment
An analysis of the relationship between organic matter and liquid and plastic limits, and grain‐specific gravity of a marine sediment was accomplished by making a stepwise adjustment in the organic content of that sediment. The sample used was from Santa Barbara Basin (off southern California) and is typical of fine‐grained marine sediments: it is a clayey silt with a common suite of...
Comments on 'Remarks on the secular change in the energy density spectrum of the geomagnetic field' by Joachim Meyer. Comments on 'Remarks on the secular change in the energy density spectrum of the geomagnetic field' by Joachim Meyer.
Meyer has discussed only the Rn aspect of the Alldredge (1984) paper he is criticising. He has ignored the pictorial demonstration of the need for higher harmonics to properly describe the secular variation field than the main field as demonstrated. This more or less independent demonstration supports the general conclusion of that paper.
Authors
L.R. Alldredge
Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska: October 1986 Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska: October 1986
No abstract available.
Authors
John B. Townshend, H.K. Rex, L.Y. Torrence
Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska: July 1986 Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska: July 1986
No abstract available.
Authors
John B. Townshend, J.E. Papp, H.K. Rex, L.Y. Torrence