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IPOD-USGS multichannel seismic reflection profile from Cape Hatteras to the Mid-Atlantic Ridge IPOD-USGS multichannel seismic reflection profile from Cape Hatteras to the Mid-Atlantic Ridge

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.
Authors
John A. Grow, Rudi G. Markl

Pleistocene barrier bar seaward of ooid shoal complex near Miami, Florida Pleistocene barrier bar seaward of ooid shoal complex near Miami, Florida

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...
Authors
Robert B. Halley, Shinn Shinn, J. Harold Hudson, Barbara H. Lidz

The effects of the α‐β phase transformation on the creep properties of hydrolytically‐weakened synthetic quartz The effects of the α‐β phase transformation on the creep properties of hydrolytically‐weakened synthetic quartz

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...
Authors
Stephen H. Kirby

Mechanical twinning in diopside Ca(Mg,Fe)Si2O6: Structural mechanism and associated crystal defects Mechanical twinning in diopside Ca(Mg,Fe)Si2O6: Structural mechanism and associated crystal defects

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...
Authors
Stephen H. Kirby, J.M. Christie

Wave propagation in soils Wave propagation in soils

No abstract available.
Authors
Roger D. Borcherdt

Beach cusps Beach cusps

No abstract available.
Authors
A. H. Sallenger

Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas

Core drilling and examination of underwater excavation on 6 reef sites in south Florida and Dry Tortugas revealed that underlying topography is the major factor controlling reef morphology. Carbon-14 dating on coral recovered from cores enables calculation of accumulation rates. Accumulation rates were found to range from 0.38 m/1000 years in thin Holocene reefs to as much as 4.85 m/1000...
Authors
E.A. Shinn, J.H. Hudson, R. B. Halley, B. H. Lidz

Limestone compaction: an enigma Limestone compaction: an enigma

Compression of an undisturbed carbonate sediment core under a pressure of 556 kg/cm2 produced a “rock” with sedimentary structures similar to typical ancient fine-grained limestones. Surprisingly, shells, foraminifera, and other fossils were not noticeably crushed, which indicates that absence of crushed fossils in ancient limestones can no longer be considered evidence that limestones...
Authors
Eugene A. Shinn, Robert B. Halley, J. Harold Hudson, Barbara H. Lidz
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