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Deformation of poorly consolidated sediment during shallow emplacement of a basalt sill, Coso Range, California Deformation of poorly consolidated sediment during shallow emplacement of a basalt sill, Coso Range, California

A 150-m-long, wedge-shaped unit of folded and faulted marly siltstone crops out between undeformed sedimentary rocks on the north flank of the Coso Range, California. The several-meter-thick blunt end of this wedge abuts the north margin of a basaltic sill of comparable thickness. Chaotically deformed siltstone crops out locally at the margin of this sill, and at one locality breccia...
Authors
W. A. Duffield, C. R. Bacon, P.T. Delaney

A history of paleoflood hydrology in the United States A history of paleoflood hydrology in the United States

The origins of paleoflood hydrology in the United States can be traced back to the beginning of the 19th century, when windgaps and watergaps in the Applachians were believed to have been eroded by extraordinary floods as large lakes that were ponded behind the ridges rapidly drained. Sediment evidence for extraordinary floods was evoked several decades later when glacial sediments in...
Authors
John E. Costa

Implications of silicic vent patterns for the presence of large crustal magma chambers Implications of silicic vent patterns for the presence of large crustal magma chambers

On the basis of the distribution of silicic vents, many volcanic fields can be grouped with (1) igneous systems that may be small and whose vent locations are controlled by regional tectonics, (2) those that include sizable crustal magma bodies which erupt at sites determined by their anomalous local stress fields, or (3) relatively small volume systems that are transitional between...
Authors
Charles R. Bacon

A constitutive equation for mass-movement behavior A constitutive equation for mass-movement behavior

A phenomenological constitutive equation can serve as a basis for modeling and classifying mass-movement processes. The equation is derived using the principles of continuum mechanics and several simplifying assumptions about mass-movement behavior. These assumptions represent idealizations of field behavior, but they appear highly justifiable in light of the geomorphological insight...
Authors
Richard M. Iverson

Mid-Atlantic Ridge coccolith and silicoflagellate biostratigraphy, Deep Sea Drilling Project Sites 558 and 563. Mid-Atlantic Ridge coccolith and silicoflagellate biostratigraphy, Deep Sea Drilling Project Sites 558 and 563.

Low-latitude coccolith zonation can be used for biostratigraphy at Mid-Atlantic Ridge sites DSDP 558 (lat. 38°N) and DSDP 563 (lat. 34°N). The low-latitude zonal sequence from lower Oligocene to Holocene is interrupted by coolwater assemblages in upper middle Miocene and by hiatuses that removed the lower Pliocene and part of the upper Pliocene. A gap in the range of zonal guide fossil...
Authors
David Bukry

Tropical Pacific silicoflagellate zonation and paleotemperature trends of the late Cenozoic Tropical Pacific silicoflagellate zonation and paleotemperature trends of the late Cenozoic

Quantitative study of late Cenozoic silicoflagellates at tropical Pacific DSDP Sites 572 and 575 shows that the greatest amplitude of fluctuation in relative paleotemperature values occurred in the late Miocene. The coolest minimum paleotemperature values (near 75 = 30) also occurred in the late Miocene. The warmest intervals (Ts = 80 to 100) occurred in the middle Miocene and late...
Authors
David Bukry

Impact on the Columbia River of an outburst of Spirit Lake Impact on the Columbia River of an outburst of Spirit Lake

A one-dimensional sediment-transport computer model was used to study the effects of an outburst of Spirit Lake on the Columbia River. According to the model, flood sediment discharge to the Columbia from the Cowlitz would form a blockage to a height of 44 feet above the current streambed of the Columbia River, corresponding to a new streambed elevation of -3 feet, that would impound the...
Authors
W. G. Sikonia

Eruption in an ice-filled caldera, Mount Veniaminof, Alaska Peninsula: A section in The United States Geological Survey in Alaska: Accomplishments during 1983 Eruption in an ice-filled caldera, Mount Veniaminof, Alaska Peninsula: A section in The United States Geological Survey in Alaska: Accomplishments during 1983

The more prominent of the two visible intracaldera cones of Mount Veniaminof went into eruption in early June 1983 and continued until early April 1984. Veniaminof is a 2,507-m-high composite cone having an 8 x 11-km summit caldera which formed 3,300-3,700 yr B.P. (Miller and Smith, 1977). The active 1.6x1.2-km cone protrudes 200 m through the glacial ice filling the caldera; it lies in...
Authors
M. Elizabeth Yount, Thomas P. Miller, Richard P. Emanuel, Frederic H. Wilson
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