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NARROW
GeoRef Subject
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all geography including DSDP/ODP Sites and Legs
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Antarctica
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East Antarctica (1)
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Transantarctic Mountains (1)
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Victoria Land (1)
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Blue Mountain (1)
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North America
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Appalachians
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Blue Ridge Province (1)
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Central Appalachians (1)
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Northern Appalachians (1)
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Piedmont (1)
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Rocky Mountains
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U. S. Rocky Mountains
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Absaroka Range (2)
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United States
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Maryland (1)
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Pennsylvania
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Cumberland County Pennsylvania (1)
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Susquehanna River (2)
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U. S. Rocky Mountains
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Absaroka Range (2)
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Wyoming
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Park County Wyoming (1)
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fossils
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microfossils (1)
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Plantae
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algae
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diatoms (1)
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geochronology methods
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tree rings (2)
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upper Pleistocene
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Tertiary
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Neogene
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igneous rocks
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igneous rocks (1)
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volcanic ash (1)
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Primary terms
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absolute age (2)
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Antarctica
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East Antarctica (1)
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Transantarctic Mountains (1)
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Victoria Land (1)
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Cenozoic
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Quaternary
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Holocene
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upper Holocene (1)
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Pleistocene
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upper Pleistocene
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Wisconsinan (1)
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Sirius Group (1)
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Tertiary
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Neogene
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Miocene (2)
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Pliocene (3)
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upper Cenozoic (1)
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education (1)
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fractures (1)
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geochronology (2)
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geology (1)
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geomorphology (6)
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glacial geology (2)
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hydrology (3)
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igneous rocks (1)
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Mesozoic
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Jurassic (1)
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Triassic (1)
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North America
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Appalachians
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Blue Ridge Province (1)
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Central Appalachians (1)
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Northern Appalachians (1)
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Piedmont (1)
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Rocky Mountains
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U. S. Rocky Mountains
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Absaroka Range (2)
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paleoclimatology (1)
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sedimentary rocks (1)
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sediments (1)
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United States
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Maryland (1)
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Pennsylvania
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Susquehanna River (2)
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U. S. Rocky Mountains
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Wyoming
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Park County Wyoming (1)
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rock formations
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Beacon Supergroup (1)
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sedimentary rocks
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sedimentary rocks (1)
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sediments
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sediments (1)
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Long-term field-based studies in geoscience teaching
Multiyear measurements of geologic processes with slow rates of change can provide valuable data sets for student learning in the classroom and opportunities for undergraduate independent research. Here, we describe three projects for which data have been collected for 34, 20, and 10 yr, respectively: the erosion of a small meandering stream, the weathering of limestone cubes, and local stream hydrology/chemistry, including discharge, dissolved and suspended load, and major ion chemistry. These data have been used at all levels of the curriculum in various ways, from visualizing basic geologic principles in introductory courses to sophisticated statistical analysis and interpretation in upper-level courses, always in a context of student research leading to discovery about Earth systems. Depending on the project and the schedule for data collection, students have played a major role in the data collection, synthesis, and interpretation while also learning valuable analytical and statistical skills. Because the data sets are the product of many classes of students, there is a strong sense of ownership of the data and thus significant quality control, making the data sets useful as baseline studies for future projects. Where the study requires frequent and time-sensitive sampling, it is more difficult for students to collect data or make measurements. They may, however, have a hand in analyzing the samples collected in order to learn analytical and interpretive techniques. In some cases, these projects have expanded to include new long-term data sets that augment the original studies.
Rivers, glaciers, landscape evolution, and active tectonics of the central Appalachians, Pennsylvania and Maryland
Abstract Welcome to the Appalachian landscape! Our field trip begins with a journey across Fall Zone (Fig. 1 ), named for the falls and rapids on streams flowing from the consolidated rocks of the Appalachians onto the unconsolidated sediments of the Coastal Plain. The eastern U.S. urban centers are aligned along the Fall Zone, the upstream limit of navigation. Typically, the rocks west of the Fall Zone are part of the Piedmont province. This province exposes the metamorphic core of the Appalachian Mountains exhumed by both tectonics and erosion. At least four major phases of deformation are preserved in Piedmont rocks, three Paleozoic convergent events that closed Iapetus, followed by Mesozoic extension that opened the Atlantic Ocean. A record of Cretaceous to Quaternary exhumation of the Appalachians is preserved as Coastal Plain sediments. Late Triassic and Jurassic erosion is preserved in the syn-extensional fault basins, such as the Newark basin, or is buried beneath Coastal Plain sediments (Fig. 1 ). The trip proceeds northwest across the Fall Zone and Piedmont and into the Newark basin. Late Triassic and Jurassic fluvial red sandstone, lacustrine gray shale, and black basalt were deposited in this basin. The Newark basin is separated from the Blue Ridge by a down to the east normal fault that locally has contemporary microseismicity. The Blue Ridge represents a great thrust sheet that was emplaced from the southeast during the Alleghenian orogeny (Permian). The summits of the Blue Ridge are commonly broad and accordant. Davis (1889) projected that accordance westward to the summits of the Ridge and Valley to define his highest and oldest peneplain—the Schooley peneplain. North and west of the Blue Ridge is the Great Valley Section of the Ridge and Valley Province (Fig. 1 ). Where we cross the Great Valley at Harrisburg, it is called the Cumberland and Lebanon valleys. This section is underlain by lower Paleozoic carbonate, shale, and slate folded and faulted during the lower Paleozoic Taconic orogeny. The prominent ridge on the west flank of the Great Valley is Blue or Kittatinny Ridge. It is the first ridge of the Ridge and Valley Province; the folded and faulted sedimentary rocks of the Appalachian foreland basin, deformed during the Alleghenian orogeny. Drainage during most of the Paleozoic was to the northwest, bringing detritus into the Appalachian foreland basin. The drainage reversed with the opening of the Atlantic Ocean and southeast-flowing streams established courses transverse to the strike of resistant rocks, like the Silurian Tuscarora Sandstone holding up Blue Mountain. West and north of the Ridge and Valley is the Allegheny Plateau, that part of the Appalachian foreland that was only gently deformed during Alleghenian shortening. Our trip will traverse that part of the plateau called the Pocono Plateau which is underlain by Devonian to Penn-sylvanian sandstone. At the conclusion of our trip, we will reverse our transverse of the Appalachians by traveling from the Pocono Plateau to the Ridge and Valley, to the Great Valley, to the Newark Basin, to the Piedmont, and then to one of the great Fall Zone cities—Philadelphia—via the Lehigh and Schuylkill rivers.
The influence of riparian vegetation on stream width, eastern Pennsylvania, USA
Pliocene-Pleistocene diatoms in Paleozoic and Mesozoic sedimentary and igneous rocks from Antarctica: A Sirius problem solved
Late Cenozoic Antarctic paleoclimate reconstructed from volcanic ashes in the Dry Valleys region of southern Victoria Land
APPALACHIAN PENEPLAINS: AN HISTORICAL REVIEW
Ice-Cored Rock Glacier, Galena Creek, Northern Absaroka Mountains, Wyoming
Tree-Ring Dating of Snow Avalanche Tracks and the Geomorphic Activity of Avalanches, Northern Absaroka Mountains, Wyoming
Tree-ring dating in several avalanche tracks in Galena Creek valley, northern Absaroka Mountains, Wyoming, is used to determine the frequency of large snow avalanches that pass below the forest line. The following criteria are used: (1) datable scars on the trees, (2) changes in growth-ring pattern from concentric to eccentric, caused by tilting, (3) changes in growth rate due to increase in photosynthesis when adjacent trees are destroyed, and (4) age of trees within a given reforested avalanche track. The first two of these criteria are most reliable. Many young trees within the avalanche tracks are protected by snow during avalanches, and they thus survive to reforest the track immediately following destruction of the larger trees. Above the forest line, avalanche boulder tongues are one of the most reliable indicators of persistent activity in alpine regions, for they are formed over a period of many years by the accumulation of debris swept out of avalanche chutes. A peculiar linear feature on the surface of the tongues is the avalanche debris tail, which consists of fine debris that was deposited by large snow avalanches downslope 5 to 10 m from a large boulder. They are thought to be formed by a mechanism similar to that by which sand shadows are formed in the lee of obstacles in river channels or on desert dunes.