Publications

An understanding of earth history depends in part on stratigraphy, a division of geology in which the distinctive features of natural units or formations of layered rocks are studied and described and names are assigned to them. The procedures for describing and naming rock units in a uniform way are incorporated in documents known as stratigraphic codes. The North American Stratigraphic...

Indicators of organic metamorphism provide valuable tools for analyzing the thermal history of tectonostratigraphic terranes. Paleotemperature estimates derived from vitrinite reflectance, for example, are more precise than values based upon inorganic mineral assemblages in low‐grade rocks. Isothermal geometries must be interpreted within the context of structural and stratigraphic data...

The late Mesozoic Coast Range ophiolite and Great Valley sequence in California were juxtaposed against the Franciscan Complex during a long tectonic history that included imbricate thrust faulting, low‐angle detachment, and high‐angle reverse faulting. Many low‐angle faults previously mapped as thrusts invariably juxtapose younger over older rocks, suggesting a normal sense of offset...

Overprinted magnetizations have been found at four localities in the Middle Jurassic Coast Range ophiolite and the overlying Upper Jurassic and Lower Cretaceous Great Valley sequence in northern California and at one locality in the partially correlative Lower Cretaceous Days Creek Formation in southwest Oregon. At Del Puerto Canyon, on the east side of the Diablo Range, a pilot study of...

No abstract available.

The protolith and metamorphic histories of Early Cretaceous blueschists that occur in Washington, Oregon, and California are remarkably similar. These blueschists are the Shuksan metamorphic suite of northwestern Washington, the Condrey Mountain schist of northern California and southern Oregon, and the Pickett Peak terrane of northern California and southwestern Oregon. We suggest that...

No abstract available.

The Ojo Alamo Sandstone of the San Juan Basin of New Mexico is composed of interbedded conglomeratic sandstone, sandstone, siltstone, and mudstone. Conglomerates are found in the western part of the basin; siliceous pebbles diminish in size both southward and eastward across the basin, becoming rare to nonexistent in the eastern part. There is great variation in the internal stratigraphy...

The Kirtland Shale or Fruitland Formation directly underlies the Cretaceous-Tertiary boundary throughout most of the San Juan Basin of northwest New Mexico and southwest Colorado. These formations have been known to be Late Cretaceous in age since the early 1900s. Now, with the greatly renewed interest in rocks adjacent to mass extinction boundaries, it is important to place more precise...

No abstract available.

A real-time system for issuing warnings of landslides during major storms is being developed for the San Francisco Bay region, California. The system is based on empirical and theoretical relations between rainfall and landslide initiation, geologic determination of areas susceptible to landslides, real-time monitoring of a regional network of telemetering rain gages, and National...

No abstract available.