6 research outputs found
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Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon
This study illustrates geoarchaeological and paleoenvironmental approaches to the
investigation of an active margin coastal setting and provides examples of how information gleaned through examination of the stratigraphic record can reveal depositional signatures that provide insights into the geomorphic and tectonic forces active within coastal river basins. Three case studies from the southern Oregon coast illustrate the complex relationship between tectonics and geomorphic processes along an active margin coast such as Oregon's Cascadia subduction zone. This work illustrates that the differential preservation of late Pleistocene-age terrestrial deposits in Oregon's coastal landscape, and the early cultural sites they may contain, is not random but can be closely related to larger tectonogeomorphic processes operating at local and regional scales. Detailed subsurface investigation of one case study site, the lower Sixes River valley,
reveals a complex history of depositional environment evolution in relation to geomorphic and tectonic forces. Litho- and biostratigraphic data sets are used to develop a depositional environment reconstruction for the lower Sixes River site through time. This reconstruction of the depositional environment from the late Pleistocene to the present indicates a transgressive evolution that differs from models of transgressive coastal facies and from other studied Northwest coast estuarine life histories. Factors such as eustatic sea level rise, regional and local tectonic alteration of the landscape, sediment supply, or valley morphology may have played roles in the creation and preservation of this atypical depositional sequence. Litho- and biostratigraphic evidence of six Cascadia subduction zone earthquakes
younger than 6200 cal yr BP is recorded in a long sediment core from the Sixes River valley. All six of these events correlate with events previously reported for the area by Kelsey et al. (2002). At least five additional plate boundary earthquakes lowered tidal marshes and freshwater wetlands prior to 6200 cal yr BP. The presence within the lower Sixes River valley of an intertidal environment capable of recording Cascadia subduction zone earthquakes dating to the late Pleistocene and early Holocene has not been found at any other location on the Northwest coast
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A Field Report from the Sunken Village Wet Site (35MU4)
During low waters of September a wet site team, sponsored by an international grant from Japan, returned to further record the National Heritage Landmark wet site of Sunken Village (35MU4), Sauvie Island, Portland, Oregon (Figure 1). The one week project (September 16 through 22, 2007) was designed to accurately map the surface features ( especially over a hundred in situ acorn leaching pits and wooden stakes) and surface artifacts (especially lithic debitage and fauna! remains) as revealed in the limited evaluation of I 060 linear feet (320 metres) of beach before the riprap repair was permitted by the U.S. Corps of Engineers in October of 2006 (Croes, Fagan and Zehendner 2007; a PDF copy of this 2006 field work is available on the web - see References below). The project continues to be co-managed through the direct in-put by Cultural Resources Protection Specialists Eirik Thorsgard, Confederated Tribes of the Grand Ronde, and Robert Kentta, Confederated Tribes of Siletz Indians and in consultation with the Confederated Tribes of Warms Springs. A joint team provided the expertise needed to carefully map and record the Sunken Village National Historic Landmark site, consisting of(a) the SPSCC Wet Site Archaeological Investigations and Laboratory team, lead by Dr. Dale Croes, and the SPSCC Computer Aided Drafting Department, lead by Professor Michael Martin, (b) the AINW geoarchaeological and laboratory team, lead by Dr. Michele Punke and Maureen Zehendner, and ( c) the internationally known Wetland Archaeological Team from the National Institute for Cultural Heritage, Nara, Japan, lead by Dr. Akira Matsui. This project was conducted through the sponsorship of a Japanese international grant under the administration of Dr. Akira Matsui, Chief Archaeologist, National Institute for Cultural Heritage, Nara, Japan, as well as support through the SPSCC Anthropology Club, an SPSCC Exceptional Faculty grant, Jean and Ray Auel, and volunteers from Portland State University and the Oregon Archaeological Society. Dr. Matsui brought four Japanese associates to participate in the field work: Dr. Naoto Yamamoto, Dr. Toru Miyao, Dr. Atsushi Iwasaki, and Dr. Tomonori Kanno (Figure 2)
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Predictive locational modeling of late Pleistocene archaeological sites on the southern Oregon Coast using a Geographic Information System (GIS)
The search for archaeological materials dating to 15,000 yr BP along the southern Oregon coast is a formidable task. Using ethnographic, theoretical, and archaeological data, landscape resources which would have influenced land-use and occupation location decisions in the past are highlighted. Additionally, environmental data pertaining to the late Pleistocene is examined to determine what landscape features may have been used by human groups 15,000 years ago and to determine how these landscape features may have changed since that time. These landscape resource features are included in the modeling project as independent variables. The dependent variable in this modeling project is relative probability that an area will contain archaeological materials dating to the time period of interest. Two predictive locational models are created to facilitate the search process. These models mathematically combine the independent variables using two separate approaches. The hierarchical decision rule model approach assumes that decision makers in the past would have viewed landscape features sequentially rather than simultaneously. The additive, or weighted-value, approach assumes that a number of conditional preference aspects were evaluated simultaneously and that different environmental variables had varying amounts of influence on the locational choices of prehistoric peoples. Integration of the data and mathematical model structures into a Geographic Information System (GIS) allows for spatial analysis of the landscape and the prediction of locations most likely to contain evidence of human activity dating to 15,000 years ago. The process involved with variable integration into the GIS is delineated and results of the modeling procedures are presented in spatial, map-based formats
Organic light detectors: photodiodes and phototransistors
While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory