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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

Topography, structure, and mare ridges in southern Mare Imbrium and northern Oceanus Procellarum Topography, structure, and mare ridges in southern Mare Imbrium and northern Oceanus Procellarum

The gross topography in southern Mare Imbrium and northern Oceanus Procellarum correlates with the buried structure and deposits of the Imbrium Basin and its rim, and many of the mare slopes may be depositional and reflect the pre-existing major features of the basin. Post-depositional, local distortion of the mare surface, however, is present and in many places associated with mare...
Authors
Baerbel K. Lucchitta

Crater clusters and light mantle at the Apollo 17 site: A result of secondary impact from Tycho Crater clusters and light mantle at the Apollo 17 site: A result of secondary impact from Tycho

The morphologies of Tycho secondary craters and their ejecta deposits were studied using full-Moon, Lunar-Orbiter, and Apollo panoramic photographs. These data were compared with similar data for the secondary craters and light mantle of the Apollo 17 landing site. The results indicate that (1) the central crater cluster and the light mantle can be attributed to Tycho, (2) the dominant...
Authors
Baerbel K. Lucchitta
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