Thirty Thousand Years of Vegetation Changes in the Alabama Hills, Owens Valley, California

1995 ◽  
Vol 43 (2) ◽  
pp. 238-248 ◽  
Author(s):  
Peter A. Koehler ◽  
R.Scott Anderson
Keyword(s):  
Sierra Nevada ◽  
Vegetation Change ◽  
Vegetation Changes ◽  
Owens Valley ◽  
Juniperus Osteosperma ◽  
Pollen Types ◽  
Yucca Brevifolia ◽  
Utah Juniper ◽  
Coleogyne Ramosissima ◽  
Eastern Sierra Nevada

AbstractTwenty packrat (Neotoma) middens recovered from three sites (1265-1535 m) in the Alabama Hills, Inyo County, California, provide a ca. 31,450-yr record of vegetation change. Located ca. 7 km east of the Sierra Nevada, the middens document that Utah juniper (Juniperus osteosperma), Joshua tree (Yucca brevifolia), and bitterbush (Purshia tridentata) occupied the site between 31,450 and 19,070 yr B.P. Joshua tree and bitterbush departed by ca. 17,760 yr B.P., with cliffrose (Purshia mexicana) and joint-fir (Ephedra viridis) appearing. By 13,350 yr B.P., blackbush (Coleogyne ramosissima) and cholla (Opuntia echinocarpa) entered the record. Between 9540 and 7990 yr B.P., Utah juniper and other species now extralocal to the sites departed and modern components such as wolfberry (Lycium andersonii) and rubber rabbitbrush (Chrysothamnus teretifolius) appeared. The middle Holocene records little variation in plant macrofossil composition; however, pollen analysis reflects an increase in aquatic pollen types which might suggest more-open conditions. The transition to the modern vegetation associations at the sites occurred after ca. 2800 yr B.P. The record from the Alabama Hills correlates well with that of other regional vegetation data but documents conditions of increasing aridity earlier than many other packrat midden sites. A shift in understory vegetation between 19,070 and 17,760 yr B.P. may reflect a transition from glacial maximum to post-maximum conditions in the eastern Sierra Nevada.

Relative Dating of Terraces of the Owens River, Northern Owens Valley, California, and Correlation with Moraines of the Sierra Nevada

1994 ◽  
Vol 42 (3) ◽  
pp. 266-276 ◽  
Author(s):  
Nicholas Pinter ◽  
Edward A. Keller ◽  
Robert B. West
Keyword(s):  
Sierra Nevada ◽  
Soil Development ◽  
Early Holocene ◽  
Owens Valley ◽  
Weathering Processes ◽  
Relative Dating ◽  
Altered Surface ◽  
The Difference ◽  
Absolute Age ◽  
Eastern Sierra Nevada

AbstractIn the northern Owens Valley, the Owens River has cut and preserved three terraces uplifted above its modern floodplain. We have analyzed soils and used other relative-dating techniques in order to differentiate the terrace surfaces, to correlate from the terraces to moraines of the eastern Sierra Nevada, and to test the effects of relief and climatic differences on relative-dating results. Most of the relative-dating techniques attempted were successful in differentiating the terraces of the Owens River sequence. In addition, weathering rinds, soil descriptions, and an early Holocene 14 C date for the youngest terrace support correlation of the three terrace levels with the three post-Sherwin-age glacial stages (Tioga, Tahoe, and pre-Tahoe) found in nearby canyons of the Sierra Nevada. Other relative-dating techniques that are commonly employed, however, suggest distinct differences between the terrace and moraine sequences. These differences probably reflect the difference in relief, such that slow erosion of the moraine crests may have retarded soil development relative to the flat terrace surfaces and altered surface-weathering processes. Use of relative-dating analyses to correlate between dissimilar geomorphic systems requires caution but use of a broad range of techniques and absolute-age calibration may make correlation possible.

PRELIMINARY STRATIGRAPHY AND CHRONOLOGY OF CONVICT LAKE (CA), EASTERN SIERRA NEVADA

2019 ◽  
Author(s):  
Michael M. McGlue ◽  
◽  
Edward W. Woolery ◽  
Morgan Black ◽  
Ali Almayahi
Keyword(s):  
Sierra Nevada ◽  
Eastern Sierra Nevada

scholarly journals Vegetation Dynamic Assessment by NDVI and Field Observations for Sustainability of China’s Wulagai River Basin

2021 ◽  
Vol 18 (5) ◽  
pp. 2528
Author(s):  
Panpan Chen ◽  
Huamin Liu ◽  
Zongming Wang ◽  
Dehua Mao ◽  
Cunzhu Liang ◽  
...  
Keyword(s):  
Species Diversity ◽  
River Basin ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Dynamic Assessment ◽  
Indicator System ◽  
Vegetation Changes ◽  
Vegetation Dynamic ◽  
Management Policies ◽  
The Impact

Accurate monitoring of grassland vegetation dynamics is essential for ecosystem restoration and the implementation of integrated management policies. A lack of information on vegetation changes in the Wulagai River Basin restricts regional development. Therefore, in this study, we integrated remote sensing, meteorological, and field plant community survey data in order to characterize vegetation and ecosystem changes from 1997 to 2018. The residual trend (RESTREND) method was utilized to detect vegetation changes caused by human factors, as well as to evaluate the impact of the management of pastures. Our results reveal that the normalized difference vegetation index (NDVI) of each examined ecosystem type showed an increasing trend, in which anthropogenic impact was the primary driving force of vegetation change. Our field survey confirmed that the meadow steppe ecosystem increased in species diversity and aboveground biomass; however, the typical steppe and riparian wet meadow ecosystems experienced species diversity and biomass degradation, therefore suggesting that an increase in NDVI may not directly reflect ecosystem improvement. Selecting an optimal indicator or indicator system is necessary in order to formulate reasonable grassland management policies for increasing the sustainability of grassland ecosystems.

Microseismicity and tectonics of the Nevada Seismic Zone

1971 ◽  
Vol 61 (5) ◽  
pp. 1413-1432 ◽  
Author(s):  
Frank J. Gumper ◽  
Christopher Scholz
Keyword(s):  
Sierra Nevada ◽  
Focal Mechanism ◽  
Basin And Range ◽  
Mono Lake ◽  
Tectonic Activity ◽  
Seismic Zone ◽  
Owens Valley ◽  
Western Basin ◽  
Focal Mechanism Solutions ◽  
Composite Focal Mechanism

abstract Microseismicity, composite focal-mechanism solutions, and previously-published focal parameter data are used to determine the current tectonic activity of the prominent zone of seismicity in western Nevada and eastern California, termed the Nevada Seismic Zone. The microseismicity substantially agrees with the historic seismicity and delineates a narrow, major zone of activity that extends from Owens Valley, California, north past Dixie Valley, Nevada. Focal parameters indicate that a regional pattern of NW-SE tension exists for the western Basin and Range and is now producing crustal extension within the Nevada Seismic Zone. An eastward shift of the seismic zone along the Excelsior Mountains and left-lateral strike-slip faulting determined from a composite focal mechanism indicate transform-type faulting between Mono Lake and Pilot Mountain. Based on these results and other data, it is suggested that the Nevada Seismic Zone is caused by the interaction of a westward flow of mantle material beneath the Basin and Range Province with the boundary of the Sierra Nevada batholith.

The Cedar Mountain, Nevada, earthquake of December 20, 1932*

1934 ◽  
Vol 24 (4) ◽  
pp. 345-384 ◽  
Author(s):  
Vincent P. Gianella ◽  
Eugene Callaghan
Keyword(s):  
Sierra Nevada ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Relative Movement ◽  
East Side ◽  
Owens Valley ◽  
The West ◽  
Horizontal Movement ◽  
San Andreas

Summary The Cedar Mountain, Nevada, earthquake took place at about 10h 10m 04s p.m., December 20, 1932. It was preceded by a foreshock noted locally and followed by thousands of aftershocks, which were reported as still continuing in January 1934. No lives were lost and there was very little damage. The earthquake originated in southwest central Nevada, east of Mina. A belt of rifts or faults in echelon lies in the valley between Gabbs Valley Range and Pilot Mountains on the west and Cedar Mountain and Paradise Range on the east. The length of this belt is thirty-eight miles in a northwesterly direction, and the width ranges from four to nine miles. The rifts consist of zones of fissures which commonly reveal vertical displacement and in a number of places show horizontal displacement. The length of the rifts ranges from a few hundred feet to nearly four miles, and the width may be as much as 400 feet. The actual as well as indicated horizontal displacement is represented by a relative southward movement of the east side of each rift. The echelon pattern of the rifts within the rift area indicates that the relative movement of the adjoining mountain masses is the same. The direction of relative horizontal movement corresponds to that along the east front of the Sierra Nevada at Owens Valley and on the San Andreas rift.

Sierra Nevada-Great Basin boundary zone: Earthquake hazard related to structure, active tectonic processes, and anomalous patterns of earthquake occurrence

1980 ◽  
Vol 70 (5) ◽  
pp. 1557-1572
Author(s):  
J. D. VanWormer ◽  
Alan S. Ryall
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Temporal Variations ◽  
Mono Lake ◽  
Local Network ◽  
Low Velocity ◽  
Owens Valley ◽  
Walker Lake ◽  
Fault Plane Solutions ◽  
The North

abstract Precise epicentral determinations based on local network recordings are compared with mapped faults and volcanic features in the western Great Basin. This region is structurally and seismically complex, and seismogenic processes vary within it. In the area north of the rupture zone of the 1872 Owens Valley earthquake, dispersed clusters of epicenters agree with a shatter zone of faults that extend the 1872 breaks to the north and northwest. An area of frequent earthquake swarms east of Mono Lake is characterized by northeast-striking faults and a crustal low-velocity zone; seismicity in this area appears to be related to volcanic processes that produced thick Pliocene basalt flows in the Adobe Hills and minor historic activity in Mono Lake. In the Garfield Hills between Walker Lake and the Excelsior Mountains, there is some clustering of epicenters along a north-trending zone that does not correlate with major Cenozoic structures. In an area west of Walker Lake, low seismicity supports a previous suggestion by Gilbert and Reynolds (1973) that deformation in that area has been primarily by folding and not by faulting. To the north, clusters of earthquakes are observed at both ends of a 70-km-long fault zone that forms the eastern boundary of the Sierra Nevada from Markleeville to Reno. Clusters of events also appear at both ends of the Dog Valley Fault in the Sierra west of Reno, and at Virginia City to the east. Fault-plane solutions for the belt in which major earthquakes have occurred in Nevada during the historic period (from Pleasant Valley in the north to the Excelsior Mountains on the California-Nevada Border) correspond to normaloblique slip and are similar to that found by Romney (1957) for the 1954 Fairview Peak shock. However, mechanisms of recent moderate earthquakes within the SNGBZ are related to right- or left-lateral slip, respectively, on nearly vertical, northwest-, or northeast-striking planes. These mechanisms are explained by a block faulting model of the SNGBZ in which the main fault segments trend north, have normal-oblique slip, and are offset or terminated by northwest-trending strike-slip faults. This is supported by the observation that seismicity during the period of observation has been concentrated at places where major faults terminate or intersect. Anomalous temporal variations, consisting of a general decrease in seismicity in the southern part of the SNGBZ from October 1977 to September 1978, followed by a burst of moderate earthquakes that has continued for more than 18 months, is suggestive of a pattern that several authors have identified as precursory to large earthquakes. The 1977 to 1979 variations are particularly noteworthy because they occurred over the entire SNGBZ, indicating a regional rather than local cause for the observed changes.

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