Publications

Radiocarbon ages have been published for nine basaltic lava flows on the island of Hawaii; the ages range from 2600 to somewhat older than 17,900 years B.P. By using the Thelliers' method in vacuum, geomagnetic paleointensity values were obtained from eight of the lavas; the ninth proved unsuitable. The paleointensities for the four youngest flows (2600–4600 years B.P.) yield virtual...

Landsliding is a common problem in eastern Fairfax County, an area underlain by Potomac Group (Lower Cretaceous) Coastal Plain deposits of silt and clay interbedded and interfingered with sand and gravel. The slides commonly are present in clay and silt that, on the basis of laboratory tests, appear to be much too strong to have failed. However, the very plastic silt and clay deposits...

The preliminary geomagnetic data included here is made available to scientific personnel and organizations, as part of a cooperative effort and on a data exchange basis because of the early need by some users. To avoid delay, all of the data is copied from original forms processed at the observatory; therefore it should be regarded as preliminary.

The preliminary geomagnetic data included here is made available to scientific personnel and organizations, as part of a cooperative effort and on a data exchange basis because of the early need by some users. To avoid delay, all of the data is copied from original forms processed at the observatory; therefore it should be regarded as preliminary.

The 10-day recorder seismic system used by the USGS since 1965 has been modified substantially to improve its dynamic range and frequency response, to decrease its power consumption and physical complexity, and to make its recordings more compatible with other NCER systems to facilitate data processing. The principal changes include: 1. increasing tape speed from 15/160 ips to 15/80 ips

The preliminary geomagnetic data included here is made available to scientific personnel and organizations, as part of a cooperative effort and on a data exchange basis because of the early need by some users. To avoid delay, all of the data is copied from original forms processed at the observatory; therefore it should be regarded as preliminary.

A 3,400-km-long multichannel seismic-reflection profile from Cape Hatteras to the Mid-Atlantic Ridge was acquired commercially under contract to the National Science Foundation and the U.S. Geological Survey. These data show evidence for massive erosion of the continental slope, diapirs at the base of the continental slope, and mantle reflections beneath the Hatteras Abyssal Plain.

An ooid sand barrier bar of Pleistocene age was deposited along the seaward side of an ooid shoal complex southwest of Miami, Florida. The bar is 35 km long, about 0.8 km wide, elongate parallel with the trend of the ooid shoal complex and perpendicular to channels between individual shoals. A depression 1.6 km wide, interpreted as a back-barrier channel, isolates the bar from the ooid...

Nine rectangular prisms of hydro‐thermally‐grown synthetic quartz crystals with 900 atomic ppm H+ were loaded in compression at 1400 bars stress and temperatures between 403 and 764°C. The a and c directions were at 45° to the compression direction, and the slip system appears to operate over the entire range of temperatures. The strain vs. time curves were sigmoidal in shape; an...

iopside twins mechanically on two planes, (100) and (001), and the associated macroscopic twinning strains are identical (Raleigh and Talbot, 1967). An analysis based on crystal structural arguments predicts that both twin mechanisms involve shearing of the (100) octahedral layers (containing Ca2+, Mg2+ and Fe2+ ions) by a magnitude of c/2. Small adjustments or shuffles occur in the...

No abstract available.

No abstract available.