Geomagnetic polarity epochs: Sierra Nevada II
Science
By: A. Cox, Richard R. Doell, and G. Brent Dalrymple
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Abstract
Ten new determinations on volcanic extrusions in the Sierra Nevada with potassium-argon ages of 3.1 million years or less indicate that the remanent magnetizations fall into two groups, a normal group in which the remanent magnetization is directed downward and to the north, and a reversed group magnetized up and to the south. Thermomagnetic experiments and mineralogic studies fail to provide an explanation of the opposing polarities in terms of mineralogic control, but rather suggest that the remanent magnetization reflects reversals of the main dipole field of the earth. All available radiometric ages are consistent with this field-reversal hypothesis and indicate that the present normal polarity epoch (N1) as well as the previous reversed epoch (R1) are 0.9 to 1.0 million years long, whereas the previous normal epoch (N2) was at least 25 percent longer.
Suggested Citation
Cox, A., Doell, R., and Dalrymple, G.B., 1963, Geomagnetic polarity epochs: Sierra Nevada II: Science, v. 142, no. 3590, p. 382-385, https://doi.org/10.1126/science.142.3590.382.b.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Geomagnetic polarity epochs: Sierra Nevada II |
| Series title | Science |
| DOI | 10.1126/science.142.3590.382.b |
| Volume | 142 |
| Issue | 3590 |
| Year Published | 1963 |
| Language | English |
| Publisher | American Association for the Advancement of Science |
| Description | 4 p. |
| First page | 382 |
| Last page | 385 |
| Country | United States |
| State | California |
| Other Geospatial | Sierra Nevada |