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Full-Text Articles in Physical Sciences and Mathematics
Quaternary Geology And Geochronology Of The Uppermost Arkansas Valley, Colorado- Glaciers, Ice Dams, Landslides, And Floods, James P. Mccalpin
Quaternary Geology And Geochronology Of The Uppermost Arkansas Valley, Colorado- Glaciers, Ice Dams, Landslides, And Floods, James P. Mccalpin
James P. McCalpin
This field trip to the uppermost Arkansas Valley of central Colorado is based mainly on work performed since 2008, in an area with a long history of bedrock mapping by renowned geologists of the U.S. Geological Survey beginning in the 1880s (e.g. Emmons, 1886). The Quaternary features of the region were first described by Capps in 1909. Despite over 100 years of intermittent geologic studies here, there were still new discoveries to be made in the past few years. Day 1 of the trip emphasizes landslides (in the morning) and glacial deposits (in the afternoon). The “take-home messages” of the …
Ridgetop Splitting, Spreading, And Shattering Related To Earthquakes In Southern California, James P. Mccalpin
Ridgetop Splitting, Spreading, And Shattering Related To Earthquakes In Southern California, James P. Mccalpin
James P. McCalpin
Our mapping documents that anomalous ridgetop landforms are numerous in the San Gabriel and Santa Susana Mountains, and that many sites (37% of the San Gabriel sites, 16% of the Santa Susana sites) are not associated with any visible signs of landsliding. These sites may represent deep-seated gravitational spreading due to earthquake shaking. However, our factor analysis indicates that the spatial distribution of these suspected spreading landforms, with respect to ridge relief and distance to Late Quaternary faults, is essentially identical to that of landslides. Thus, it seems that if these spreading landforms represent the results of earthquake shaking, than …
Spatial And Temporal Analysis Of 1200 Landslides In A 900km2 Area, Middle Rocky Mountains, Wyoming, U.S.A., James P. Mccalpin
Spatial And Temporal Analysis Of 1200 Landslides In A 900km2 Area, Middle Rocky Mountains, Wyoming, U.S.A., James P. Mccalpin
James P. McCalpin
An inventory of approximately 1200 landslides in a 900 km2 area in the Salt River Range, western Wyoming, U.S.A., reveals regional and temporal controls on the landsliding process. Sliding is strongly controlled by eight weak formations in the 21 stratigraphic units of Cambrian through Cretaceous age. Morphologic dating of slides suggests that rockslides, slump-flows, and debris flows have occurred rather uniformly in time within the Holocene. In contrast, earthflows seem to be triggered more by cool/wet climatic epicycles in the last 5,000 years.
Field Trip Roadlog For The Bear River Landslide Complex, James P. Mccalpin
Field Trip Roadlog For The Bear River Landslide Complex, James P. Mccalpin
James P. McCalpin
The Bear River Landslide Complex occurs where the unconsolidated sediments of the Bear River Delta have been incised to a depth of 350 to 490 feet (106-150 m) north of Preston, Idaho. The slides are the result of the high pore pressure in confined aquifers in the deltaic sediments. High but variable volumes of groundwater flow and the laterally discontinuous nature of the deltaic sediments result in the varied types of earth movements found within the Landslide Complex. Landslide activity occurs during years of above average precipitation, and has been exacerbated by increased recharge from reservoirs and irrigation canals constructed …
The Bear River Landslide Complex, Preston, Idaho: Geologic Considerations And Historical Perspectives, James P. Mccalpin
The Bear River Landslide Complex, Preston, Idaho: Geologic Considerations And Historical Perspectives, James P. Mccalpin
James P. McCalpin
The Bear River Landslide Complex is a series of earth movements in northern Cache Valley, north of Preston, Idaho. The landslides occur in unconsolidated sediments of the Pleistocene Bear River Delta which formed where the river entered Lakes Bonneville and Provo. The Lake Bonneville delta deposits are up to 490 feet (150 m) thick and consist of a lower alluvial coarse sand and gravel unit, a middle delta front fine sand and silt unit, and an upper pro-delta clay up to 50 feet (15 m) thick. The interbedded character of the fine sands, silts, and clays, together with abrupt lateral …
Preliminary Age Classification Of Landslides For Inventory Mapping, James P. Mccalpin
Preliminary Age Classification Of Landslides For Inventory Mapping, James P. Mccalpin
James P. McCalpin
A preliminary age classification for landslides is proposed for inventory mapping, based on morphologic criteria visible on aerial photographs. Because landslide scars and deposits are generally disequilibrium landforms, they progress through observable morphologic stages as they age. Four age classes are distinguished: 1) active; 2) inactive-young; 3) inactive-mature; 4) inactive-old. Each age class reflects the age of latest movement only. The morphologic "freshness" of each part of the landslide must be evaluated, including: the head scarp, lateral scarps, marginal drainage, internal scarps and blocks, internal drainage pattern, vegetation type and density, and toe morphology. Morphologic parameters defined from air photos …