In the Confidence Hills of southern Death Valley, California, sedimentary rocks formed during the approximate period 2.4 - 1.5 Million years ago are exposed. This time period spans several documented polarity reversals associated with the Reunion and Olduvai subchrons. Since the sediments in this area were deposited at a very high rate, we can obtain detailed records of these reversals. Furthermore, the beds are severely tilted and freshly exposed along erosional channels cutting nearly perpendicular to the strike of the bedding. Variations in tilt allow us to perform fold tests between the erosional channels.
The first stage of this project, after locating and identifying the reversals present in the exposed sections, was to study the upper Olduvai reversal (~1.79 Ma) in detail. This produced the first fold test ever on transitional directions from a geomagnetic field reversal, and some perplexing results from a novel anisotropy study of the sediments involved. See the publication list below for more information.
The next stage, which is now underway, will be a detailed study of the lower Olduvai transition. Additional studies will include more anisotropy work, analyses of lithological controls on inclination shallowing, and a detailed study of the Reunion event or subchron.
Holt, J.W., J.L. Kirschvink, The upper Olduvai geomagnetic field reversal from Death Valley, California: a fold test of transitional directions, Earth and Planetary Science Letters 133, 475-491, 1995. Click for abstract
Quidelleur, X., J.W. Holt, and J.-P. Valet, Confounding influence of magnetic fabric on sedimentary records of a field reversal, Nature 374, 246-249, 1994.
Back to Caltech Paleomag Lab page.