Project combines seismic and magnetotelluric surveying to address the Sierran root question

Mt. Whitney, the highest peak in the contiguous United States, lies less than 150 km from Death Valley, the nation's lowest point (Figure 1). Despite the nearness of these physiographic features, their geological settings vary markedly. What geologic processes lead to a high mountain range adjacent to a highly extending region? This is the Sierran root question; its answer depends on better understanding of the region's deep structure. Although the rocks exposed at the Sierra's surface have been well characterized, little is known about the rocks at depth and the tectonic processes that continue to shape Mt. Whitney and Death Valley. To study the region's deep structure, the Southern Sierra Continental Dynamics (SSCD) project was organized. In September 1993 an SSCD multidisciplinary consortium employed both magnetotelluric soundings and closely spaced seismic recorders in the High Sierra for the first time to examine the crustal and upper mantle structure of the Sierra Nevada and the adjacent Basin and Range.