Data for: A high-resolution climate history of geochemical and biological proxies from a tropical freshwater wetland located in the Kenyan Rift Valley
Loboi data repository file contains the raw data presented in Goman et al from the Loboi Wetland,... more Loboi data repository file contains the raw data presented in Goman et al from the Loboi Wetland, kenya
Data for: High-resolution climate history of a tropical freshwater wetland, geochemical and biological proxies
This file contains surface and subsurface data from sediment cores from Loboi wetland, Kenya. Sur... more This file contains surface and subsurface data from sediment cores from Loboi wetland, Kenya. Surface samples: seed macrophyte and testate amoebae data, geochemistry Core samples C1: seed macrophyte and testate amoebae data, geochemistry, magnetic susceptibility C7: geochemistry, magnetic susceptibility Papyrus: geochemistry, magnetic susceptibility Soil pit: geochemistry,
Despite several decades of research focusing on prehispanic human ecology, debate continues over ... more Despite several decades of research focusing on prehispanic human ecology, debate continues over the impact of climatic and anthropogenic landscape change on human populations in Mesoamerica. One problem in identifying the cause of this change is the lack of high-resolution paleo-environmental data from many regions. The southern Mexican highlands, in particular, have yielded few paleoenvironment data, yet have a rich and diverse cultural history. The sedimentary record from Laguna Minucúa, located within the Sierra Madre del Sur, Oaxaca, offers an exceptional opportunity to address human and environmental interactions in the region. Minucúa is a small (~0.25 ha), currently shallow pond with no apparent inlets or outlets. We retrieved two sediment cores from the site (3.5 m and 5.6 m long). The cores are highly laminated. Core chronology was developed with paleomagnetic secular variation data and compared with couplet counts and limited radiometric measurements. These data indicate that the Minucúa record at least spans the last 4500 ± 100 years. We discuss preliminary results that assess long-term environmental change for the region through examination of geochemical and magnetic susceptibility data. In particular, we discuss in more detail a 500 year time slice which encompasses the period known as the "Classic Collapse." The record indicates overall dry conditions but with two extended wet periods experienced between 1160 and 1120 cal yr BP and 1060e1000 cal yr BP We place our findings in the context of current archaeological and paleoclimatological research in Oaxaca.
Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelih... more Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelihood of a short and intermittent record of deposition. Groundwater-fed wetlands associated with these climate-sensitive playas, however, preserve changes in hydrologic budget and are thus valuable archives for semiarid regions. This study examines the paleoecological record of a groundwater-fed wetland from Lake Solai, Kenya. Biological proxies are used to reconstruct paleoenvironmental change and climate impacts over the past millennium. Dry conditions persisted between CE 1115 and 1490, followed by wetter conditions during the Little Ice Age. Near surface sediments indicate increasing anthropogenic impact through pastoralism.
In the Land of the Sky: Recent Paleoenvironmental Research From Coastal Oaxaca, Mexico
The Lower Río Verde Valley of Oaxaca has had a long and complex cultural history in part shaped b... more The Lower Río Verde Valley of Oaxaca has had a long and complex cultural history in part shaped by significant landscape change that ocurred 2300 years ago, when the Río Verde river changed morphology from a meandering to a braided form. These changes were precipitated by anthropogenic landuse impacts in the highland valleys of Oaxaca over 125 linear km to
Polity and Ecology in Formative Period Coastal Oaxaca, 2013
The studies on the effect of electron irradiation on the current voltage characteristics of comme... more The studies on the effect of electron irradiation on the current voltage characteristics of commercially available bipolar transistor (BJT) and MOSFETs are carried out at elevated temperature. A small home-made furnace with PID temperature controller is used to rise the temperature of the devices during irradiation. The irradiation induced degradation of the device parameters is found to decrease by increasing the temperature of the devices during irradiation. However, the effect of irradiation induced degradation on the characteristics of the devices is observed even at temperatures as high as 300 o C. This indicates that creation of defects dominates over simultaneous thermal annealing of these defects even at high temperatures.
Multiproxy paleoecological reconstruction of prehistoric land-use history in the western region of the lower Río Verde Valley, Oaxaca, Mexico
The Holocene, 2010
Paleoecological archives from three paleomeander sites and one archeological feature located in t... more Paleoecological archives from three paleomeander sites and one archeological feature located in the lower Río Verde Valley, Oaxaca, Mexico, are used to develop a spatial understanding of the patterns of prehistoric agricultural land use over the last ~3000 years. Multiproxy paleoecological data at each site (i.e. magnetic susceptibility, micro- and macroscopic charcoal, pollen and stable carbon isotopes) provide a history of land use. By examining the spatial differences in agricultural indicators at all the sites through time, augmented with our understanding of changes in demography and settlement patterns determined through the archeological record, we are able to reconstruct the complex human/land interactions in the western portion of the valley.
Polity and Ecology in Formative Period Coastal Oaxaca, 2013
Barber 6. defining community and status at outlying sites during the terminal Formative Period Sa... more Barber 6. defining community and status at outlying sites during the terminal Formative Period Sarah B. Barber 7. coastal/Highland interaction in oaxaca, mexico: the Perspective from san Francisco de arriba Andrew Workinger 8. Examining ceramic Evidence for the Zapotec imperialism Hypothesis in the lower río verde region of oaxaca, mexico Marc N. Levine 9. From Flesh to clay: Formative Period iconography from oaxaca's lower río verde valley Guy David Hepp and Arthur A. Joyce 10. coastal oaxaca and Formative developments in mesoamerica Christopher A.
Data for: A high-resolution climate history of geochemical and biological proxies from a tropical freshwater wetland located in the Kenyan Rift Valley
Loboi data repository file contains the raw data presented in Goman et al from the Loboi Wetland,... more Loboi data repository file contains the raw data presented in Goman et al from the Loboi Wetland, kenya
Data for: High-resolution climate history of a tropical freshwater wetland, geochemical and biological proxies
This file contains surface and subsurface data from sediment cores from Loboi wetland, Kenya. Sur... more This file contains surface and subsurface data from sediment cores from Loboi wetland, Kenya. Surface samples: seed macrophyte and testate amoebae data, geochemistry Core samples C1: seed macrophyte and testate amoebae data, geochemistry, magnetic susceptibility C7: geochemistry, magnetic susceptibility Papyrus: geochemistry, magnetic susceptibility Soil pit: geochemistry,
Despite several decades of research focusing on prehispanic human ecology, debate continues over ... more Despite several decades of research focusing on prehispanic human ecology, debate continues over the impact of climatic and anthropogenic landscape change on human populations in Mesoamerica. One problem in identifying the cause of this change is the lack of high-resolution paleo-environmental data from many regions. The southern Mexican highlands, in particular, have yielded few paleoenvironment data, yet have a rich and diverse cultural history. The sedimentary record from Laguna Minucúa, located within the Sierra Madre del Sur, Oaxaca, offers an exceptional opportunity to address human and environmental interactions in the region. Minucúa is a small (~0.25 ha), currently shallow pond with no apparent inlets or outlets. We retrieved two sediment cores from the site (3.5 m and 5.6 m long). The cores are highly laminated. Core chronology was developed with paleomagnetic secular variation data and compared with couplet counts and limited radiometric measurements. These data indicate that the Minucúa record at least spans the last 4500 ± 100 years. We discuss preliminary results that assess long-term environmental change for the region through examination of geochemical and magnetic susceptibility data. In particular, we discuss in more detail a 500 year time slice which encompasses the period known as the "Classic Collapse." The record indicates overall dry conditions but with two extended wet periods experienced between 1160 and 1120 cal yr BP and 1060e1000 cal yr BP We place our findings in the context of current archaeological and paleoclimatological research in Oaxaca.
Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelih... more Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelihood of a short and intermittent record of deposition. Groundwater-fed wetlands associated with these climate-sensitive playas, however, preserve changes in hydrologic budget and are thus valuable archives for semiarid regions. This study examines the paleoecological record of a groundwater-fed wetland from Lake Solai, Kenya. Biological proxies are used to reconstruct paleoenvironmental change and climate impacts over the past millennium. Dry conditions persisted between CE 1115 and 1490, followed by wetter conditions during the Little Ice Age. Near surface sediments indicate increasing anthropogenic impact through pastoralism.
In the Land of the Sky: Recent Paleoenvironmental Research From Coastal Oaxaca, Mexico
The Lower Río Verde Valley of Oaxaca has had a long and complex cultural history in part shaped b... more The Lower Río Verde Valley of Oaxaca has had a long and complex cultural history in part shaped by significant landscape change that ocurred 2300 years ago, when the Río Verde river changed morphology from a meandering to a braided form. These changes were precipitated by anthropogenic landuse impacts in the highland valleys of Oaxaca over 125 linear km to
Polity and Ecology in Formative Period Coastal Oaxaca, 2013
The studies on the effect of electron irradiation on the current voltage characteristics of comme... more The studies on the effect of electron irradiation on the current voltage characteristics of commercially available bipolar transistor (BJT) and MOSFETs are carried out at elevated temperature. A small home-made furnace with PID temperature controller is used to rise the temperature of the devices during irradiation. The irradiation induced degradation of the device parameters is found to decrease by increasing the temperature of the devices during irradiation. However, the effect of irradiation induced degradation on the characteristics of the devices is observed even at temperatures as high as 300 o C. This indicates that creation of defects dominates over simultaneous thermal annealing of these defects even at high temperatures.
Multiproxy paleoecological reconstruction of prehistoric land-use history in the western region of the lower Río Verde Valley, Oaxaca, Mexico
The Holocene, 2010
Paleoecological archives from three paleomeander sites and one archeological feature located in t... more Paleoecological archives from three paleomeander sites and one archeological feature located in the lower Río Verde Valley, Oaxaca, Mexico, are used to develop a spatial understanding of the patterns of prehistoric agricultural land use over the last ~3000 years. Multiproxy paleoecological data at each site (i.e. magnetic susceptibility, micro- and macroscopic charcoal, pollen and stable carbon isotopes) provide a history of land use. By examining the spatial differences in agricultural indicators at all the sites through time, augmented with our understanding of changes in demography and settlement patterns determined through the archeological record, we are able to reconstruct the complex human/land interactions in the western portion of the valley.
Polity and Ecology in Formative Period Coastal Oaxaca, 2013
Barber 6. defining community and status at outlying sites during the terminal Formative Period Sa... more Barber 6. defining community and status at outlying sites during the terminal Formative Period Sarah B. Barber 7. coastal/Highland interaction in oaxaca, mexico: the Perspective from san Francisco de arriba Andrew Workinger 8. Examining ceramic Evidence for the Zapotec imperialism Hypothesis in the lower río verde region of oaxaca, mexico Marc N. Levine 9. From Flesh to clay: Formative Period iconography from oaxaca's lower río verde valley Guy David Hepp and Arthur A. Joyce 10. coastal oaxaca and Formative developments in mesoamerica Christopher A.
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