Publications

The China Digital Seismograph Network (CDSN) is being designed and installed to provide the People's Republic of China with the facilities needed to create a national digital database for earthquake research. The CDSN, which is being developed jointly by the PRC State Seismological Bureau and the U.S. Geological Survey, will consist initially of nine digitally-recording seismograph stations, a dat

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The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This effort has r

We carried out an extensive paleointensity study of the 15.5±0.3 m.y. Miocene reversed‐to‐normal polarity transition recorded in lava flows from Steens Mountain (south central Oregon). One hundred eighty‐five samples from the collection whose paleodirectional study is reported by Mankinen et al. (this issue) were chosen for paleointensity investigations because of their low viscosity index, high C

The 87Sr/86Sr ratios and the activity ratios of 234U/238U and 230Th/238U have been measured in dolomites from a 168-m-deep core taken on the island of San Salvador, Bahamas. These data suggest two periods of dolomitization. The first episode dolomitized Miocene age sediments during the latest Miocene, and the second dolomitized the Pliocene portion of the core and was still active as recently as 1

A widespread rhodolith facies occurs within middle Eocene limestones of Eua, Tonga (Fig. 1). These limestones, first described by Hoffmeister (1932), represent a portion of a broad, early Tertiary platform that developed in the Tonga area prior to disruption and uplift by later Tertiary plate movements (Kroenke and Tongilava 1975). Algal rhodoliths form beds several meters thick within Eocene lime

GEOPROBE (Geological Processes Bottom Environmental) tripods were used to measure bottom currents, pressure, and light transmission and scattering and to obtain time-series photographs of the sea floor at depths of 23 m and 67 m on San Pedro shelf between 18 April and 6 June 1978. Winds were light (< 5 m/s) with a mean direction from the southwest throughout the measurement period. Hourly averaged

In contrast to the rarity of such observations a decade ago, seismic reflecting and refracting horizons are now being observed to Moho depths under continental shelves in a number of places. These observations provide knowledge of the entire crustal thickness from the shoreline to the oceanic crust on passive margins and supplement Consortium for Continental Reflection Profiling (COCORP)-type meas

Necker Ridge, Horizon Guyot and S.P. Lee Guyot in the Central Pacific were sampled, seismically surveyed, and photographed by bottom cameras in order to better understand the distribution, origin, and evolution of ferromanganese crusts. Necker Ridge is over 600 km long with a rugged crest, pods of sediment to 146 m thick, slopes that average 12° to 20°, and debris aprons that cover some of the low

High-resolution, single-channel and multichannel seismic-reflection profiles in the New York Bight provide 7 crossings of a 50-km-long fault that trends north-northeast for 30 km from its southern end, then bends northeast, and may continue northward beneath Long Island. Displacement, which is consistently down to the west, decreases upsection and suggests a growth fault. Dip of the fault is near

A major fault cutting through most of the crust can be identified and mapped on the Long Island platform using multichannel seismic reflection profiles and magnetic data. The fault, here called the Block Island fault (BIF), strikes north-northeast, dips westward at low angle, and does not resemble the thin-skinned thrust faulting observed in the foreland of the Appalachians. The BIF is located wit

Seismic profiles and bathymetric contours reveal a drowned barrier spit on Jeffreys Ledge off Cape Ann, Massachusetts. Seaward-dipping internal reflectors indicate that a regressive barrier formed during the early Holocene low sea-level stillstand. Preservation of the barrier spit may have been favored by its large size (as much as 20 m thick), by an ample sediment supply from unconsolidated glaci