Title: Late Holocene droughts and cave ice harvesting by Ancestral Puebloans
Abstract Water availability for Native Americans in the southwestern United States during periods of prolonged droughts is poorly understood as regional hydroclimate records are scant or contradicting. Here, we show that radiocarbon-dated charcoal recovered from an ice deposit accumulated in Cave 29, western New Mexico, provide unambiguous evidence for five drought events that impacted the Ancestral Puebloan society between ~ AD 150 and 950. The presence of abundant charred material in this cave indicates that they periodically obtained drinking water by using fire to melt cave ice, and sheds light on one of many human–environment interactions in the Southwest in a context when climate change forced growing Ancestral Puebloan populations to exploit water resources in unexpected locations. The melting of cave ice under current climate conditions is both uncovering and threatening a fragile source of paleoenvironmental and archaeological evidence of human adaptations to a seemingly marginal environment. more »« less
Onac, B.P.
(, Proceedings of the 18th UIS Congress)
Contet, Y.
(Ed.)
The droughts are believed to have influenced settlement and subsistence strategies, agricultural intensification, demographic trends, and migration of the complex Ancestral Puebloans societies that once inhabited the American Southwest. Using precisely radiocarbon dated charcoal from an ice deposit preserved in a lava tube from El Malpais National Monument of New Mexico, we conclude that the population in the region used melted ice for drinking as early as 2000 years ago. The need of constant domestic water supply, especially during major drought events, forced Ancestral Puebloans people to venture into lava tubes and look for ice. Water availability in an already harsh environment may have influenced migrations across the landscape and caused repetitive depopulation‐repopulation of some settlement locations.
Onac, B.P.; Baumann, S.M.; Parmenter, D.S.; Weaver, E.; Sava, T.B.
(, Proceedings of the 18th UIS Congress)
Contet, Y
(Ed.)
The droughts are believed to have influenced settlement and subsistence strategies, agricultural intensification, demographic trends, and migration of the complex Ancestral Puebloans societies that once inhabited the American Southwest. Using precisely radiocarbon dated charcoal from an ice deposit preserved in a lava tube from El Malpais National Monument of New Mexico, we conclude that the population in the region used melted ice for drinking as early as 2000 years ago. The need of constant domestic water supply, especially during major drought events, forced Ancestral Puebloans people to venture into lava tubes and look for ice. Water availability in an already harsh environment may have influenced migrations across the landscape and caused repetitive depopulation‐repopulation of some settlement locations.
Arthur, Kathryn Weedman
(, World Archaeological Congress)
The homeland of the Boreda people—the highlands of southern Ethiopia—sits on the western edge of the Rift Valley, which has long been considered the birthplace of humanity. In Boreda oral traditions, caves birthed the first Boreda people and stories of Dinkinesh (Lucy, Australopithecus afarensis) intertwine with accounts of cave dwellings, stone tools, and the making of leather clothing. Caves today are perceived to be one of the three wombs of the earth according to Boreda Indigenous ontology, Etta Woga. Equated with hollows of fig trees and houses, caves are reproductive liminal spaces. Here, Boreda implore ancestors and nature spirits through technological, therapeutic, and ideological rituals to protect, heal, and transform humans. Caves are part of a network of ancestral sacred grounds that include other significant landscape formations such as high peaks, springs, and forests. Together the interaction of rock (caves), earth (mountains), water (springs), and trees (Fig) on sacred ground is held as evidence that all these elements are beings that have the agency to impact human lives. In turn humans have the responsibility to care and nurture these sacred grounds.
Olson, Elizabeth; Gillikin, David P; Piccirillo, Laura; Verheyden, Anouk; Forsyth, Alexander; Litchfield, Kirsten; Stoltenberg, Hailey; Clavel, Avery; Ramjohn, Maryam; Nazir, Saliha; et al
(, Chemical Geology)
NA
(Ed.)
Speleothem paleoclimate records from the Peruvian Andes have been interpreted to reflect the strength of the South American monsoon. While these interpretations have been verified through comparison with other regional and global climate records, the mechanics of the cave environment that facilitate the preservation of this signal with such consistency remain unstudied. Here, we present four years of environmental data from Huagapo and Pacupahuain cave, and one year from Antipayarguna cave. The data reveal that the cave environment is very stable with little to no change in temperature and 100% relative humidity year-round. This stability in cave air is juxtaposed with the monsoonal drip water pulse that increases drip rates over 40 times on average across all seven monitored drip sites. Compared to the amount-weighted precipitation average δ18Oprecip value, the cave drip water δ18ODW values are evaporatively 18O enriched during infiltration through the soil/epikarst. As the monsoonal precipitation pulse fades and drip rates decrease, changes in the drip water chemistry (trace elements Mg/Ca and Sr/Ca, dissolved inorganic carbon δ13CDW, and δ18ODW values) indicate that prior calcite precipi- tation (PCP) drives the trace element and δ13CDW variability. The δ13Cc and δ18Oc values of farmed slide calcite are highly variable. However, high drip rate and lower cave air pCO2 during the monsoon combine to increase calcite precipitation rates. This causes speleothem records from these caves to be weighted toward annual monsoon conditions. Calcite isotope values from actively growing stalagmite tops support this finding. These results suggest that speleothems from these caves are sensitive to changes in monsoon precipitation amount, because it determines the duration of the monsoon drip water pulse, and therein, the extent of dry season PCP. Further, these data indicate that heterogeneity in the dolomitic limestone massif causes offsets between the carbon isotopes and trace metal concentrations between the caves, highlighting the need to normalize these datasets when chronology-stacking these proxies.
In the southwestern United States, California (CA) is one of the most climatically sensitive regions given its low (≤250 mm/year) seasonal precipitation and its inherently variable hydroclimate, subject to large magnitude modulation. To reconstruct past climate change in CA, cave calcite deposits (stalagmites) have been utilized as an archive for environmentally sensitive proxies, such as stable isotope compositions (δ18O, δ13C) and trace element concentrations (e.g., Mg, Ba, Sr). Monitoring the cave and associated surface environments, the chemical evolution of cave drip-water, the calcite precipitated from the drip-water, and the response of these systems to seasonal variability in precipitation and temperature is imperative for interpreting stalagmite proxies. Here we present monitored drip-water and physical parameters at Lilburn Cave, Sequoia Kings Canyon National Park (Southern Sierra Nevada), CA, and measured trace element concentrations (Mg, Sr, Ba, Cu, Fe, Mn) and stable isotopic compositions (δ18O, δ2H) of drip-water and for calcite (δ18O) precipitated on glass substrates over a two-year period (November 2018 to February 2021) to better understand how chemical variability at this site is influenced by local and regional precipitation and temperature variability. Despite large variability in surface temperatures and precipitation amount and source region (North Pacific vs. subtropical Pacific), Lilburn Cave exhibits a constant cave environment year-round. At two of the three sites within the cave, drip-water δ18O and δ2H are influenced seasonally by evaporative enrichment. At a third collection site in the cave, the drip-water δ18O responds solely to precipitation δ18O variability. The Mg/Ca, Ba/Ca, and Sr/Ca ratios are seasonally responsive to prior calcite precipitation at all sites but minimally to water-rock interaction. Lastly, we examine the potential of trace metals (e.g., Mn2+and Cu2+as a geochemical proxy of recharge and find that variability in their concentrations has high potential to denote the onset of the rainy season in the study region. The drip-water composition is recorded in the calcite, demonstrating that stalagmites from Lilburn Cave, and potentially more regionally, could record seasonal variability in weather even during periods of substantially reduced rainfall.
Onac, Bogdan P., Baumann, Steven M., Parmenter, Dylan S., Weaver, Eric, and Sava, Tiberiu B. Late Holocene droughts and cave ice harvesting by Ancestral Puebloans. Retrieved from https://par.nsf.gov/biblio/10258180. Scientific Reports 10.1 Web. doi:10.1038/s41598-020-76988-1.
Onac, Bogdan P., Baumann, Steven M., Parmenter, Dylan S., Weaver, Eric, & Sava, Tiberiu B. Late Holocene droughts and cave ice harvesting by Ancestral Puebloans. Scientific Reports, 10 (1). Retrieved from https://par.nsf.gov/biblio/10258180. https://doi.org/10.1038/s41598-020-76988-1
@article{osti_10258180,
place = {Country unknown/Code not available},
title = {Late Holocene droughts and cave ice harvesting by Ancestral Puebloans},
url = {https://par.nsf.gov/biblio/10258180},
DOI = {10.1038/s41598-020-76988-1},
abstractNote = {Abstract Water availability for Native Americans in the southwestern United States during periods of prolonged droughts is poorly understood as regional hydroclimate records are scant or contradicting. Here, we show that radiocarbon-dated charcoal recovered from an ice deposit accumulated in Cave 29, western New Mexico, provide unambiguous evidence for five drought events that impacted the Ancestral Puebloan society between ~ AD 150 and 950. The presence of abundant charred material in this cave indicates that they periodically obtained drinking water by using fire to melt cave ice, and sheds light on one of many human–environment interactions in the Southwest in a context when climate change forced growing Ancestral Puebloan populations to exploit water resources in unexpected locations. The melting of cave ice under current climate conditions is both uncovering and threatening a fragile source of paleoenvironmental and archaeological evidence of human adaptations to a seemingly marginal environment.},
journal = {Scientific Reports},
volume = {10},
number = {1},
author = {Onac, Bogdan P. and Baumann, Steven M. and Parmenter, Dylan S. and Weaver, Eric and Sava, Tiberiu B.},
editor = {null}
}
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