scholarly journals Late Holocene tephrostratigraphy from Cajas National Park, southern Ecuador

2020 ◽  
Vol 47 (3) ◽  
pp. 508
Author(s):  
Stephanie H. Arcusa ◽  
Tobias Schneider ◽  
Pablo V. Mosquera ◽  
Hendrik Vogel ◽  
Darrell Kaufman ◽  
...  
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Grain Morphology ◽  
Radiocarbon Age ◽  
Sedimentary Sequences ◽  
Plant Remains ◽  
Southern Ecuador ◽  
History Of ◽  
Tephra Layers ◽  
Active Volcanoes

Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra) produced during eruptive events. In this study, sediment cores from four lakes in Cajas National Park, southern Ecuador, situated approximately 200 km downwind of active volcanoes in the Northern Andes Volcanic Zone, were analysed to document the regional history of tephra fall extending back around 3,000 a cal BP. The ages of the lacustrine sedimentary sequences were constrained using a total of 20 AMS radiocarbon ages on plant remains. The tephra layers were correlated among the lakes based on their radiocarbon age, elemental composition, colour, and grain morphology. We found five unique tephra layers, each at least 0.2 cm thick, and further constrained their ages by combining the results from two age-depth modelling approaches (clam and rbacon). The tephra layers were deposited 3,034±621, 2,027±41, 1,557±177, 733±112, and 450±70 a cal BP. The ages of all but the youngest tephra layer overlap with those of known eruptions from Tungurahua. Some tephra layers are missing as macroscopic layers in several cores, with only two of the five tephra layers visible in the sediment of three lakes. Likewise, previous studies of lake sediment cores from the region are missing the four youngest tephra layers, further highlighting the need to sample multiple lakes to reconstruct a comprehensive history of fallout events. The newly documented stratigraphic marker layers will benefit future studies of lake sediments in Cajas National Park.

scholarly journals Evidence for a hardwater radiocarbon dating effect, Wonder Lake, Denali national park and preserve, Alaska, U.S.A.

2002 ◽  
Vol 53 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Jonathan K. Child ◽  
Al Werner
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Pollen Record ◽  
Lake Area ◽  
Alaska Range ◽  
Radiocarbon Age ◽  
The North ◽  
Late Wisconsinan ◽  
Denali National Park ◽  
Age Estimates

Abstract Anderson et al. (1994) present a late Pleistocene/Holocene pollen record for lacustrine sediment cores retrieved from the north end of Wonder Lake, Denali National Park and Preserve, Alaska. Bulk radiocarbon age estimates obtained during their study suggest that either a Picea refugium persisted in the foothills of the north Alaska Range near Wonder Lake during the Late Wisconsinan, or that bulk radiocarbon age estimates are inaccurate. Subsequent cores recovered from Wonder Lake (and a near-by kettle pond) have been correlated to the Anderson et al. core and age dated using Atomic Mass Spectrometry (AMS) radiocarbon age estimates. AMS radiocarbon ages suggest that bulk radiocarbon ages from Anderson et al. (1994) are affected by hardwater conditions in Wonder Lake causing them to appear greater than 2000 14 C years too old. The corrected core chronology is consistent with documented regional vegetation changes during the glacial/interglacial transition and does not require a local Picea refugium in the Wonder Lake area during the Late Wisconsinan.

scholarly journals A Late Glacial–Holocene Tephrochronology for Glacial Lakes in Southern Ecuador

2002 ◽  
Vol 57 (3) ◽  
pp. 343-354 ◽  
Author(s):  
Donald T. Rodbell ◽  
Stefan Bagnato ◽  
Jeffrey C. Nebolini ◽  
Geoffrey O. Seltzer ◽  
Mark B. Abbott
Keyword(s):  
Sediment Cores ◽  
Late Glacial ◽  
Glacial Lakes ◽  
Element Geochemistry ◽  
The Past ◽  
Northern Half ◽  
Southern Ecuador ◽  
Pair Wise Comparison ◽  
Lake Cores ◽  
Active Volcanoes

AbstractDespite the presence of numerous active volcanoes in the northern half of Ecuador, few, if any, distal tephras have been previously recognized in the southern one third of the country. In this article, we document the presence of thin (0.1–1.0-cm-thick) distal tephras comprising glass and/or phenocrysts of hornblende and feldspar in sediment cores from five glacial lakes and one bog in Las Cajas National Park (2°40′–3°00′S, 79°00′–79°25′W). The lake cores contain from 5 to 7 tephras, and each has a diagnostic major element geochemistry as determined from electron microprobe analysis of ∼710 glass shards and ∼440 phenocrysts of feldspar and hornblende. The loss of sodium with exposure to the electron microbeam causes a 10±7 wt.% (±1σ) reduction in Na content, which we empirically determined and corrected for before correlating tephras among the sediment cores. We use a similarity coefficient to correlate among the sediment cores; pair-wise comparison of all tephras generally yields an unambiguous correlation among the cores. Six tephras can be traced among all or most of the cores, and several tephras are present in only one or two of the cores. Twenty-six accelerator mass spectrometry 14C dates on macrofossils preserved in the sediment cores provide the basis for establishing a regional tephrochronology. The widespread tephras were deposited ∼9900, 8800, 7300, 5300, 2500, and 2200 cal yr B.P. The oldest tephras were deposited ∼15,500 and 15,100 cal yr B.P., but these are not found in all cores. Two of the tephras appear correlative with volcaniclastic strata on the flanks of Volcán Cotopaxi and one tephra may correlate with strata on the flanks of Volcán Ninahuilca; both volcanoes are in central Ecuador. The absence of tephras in sediment cores correlative with the numerous eruptions of active volcanoes of the past two millennia implies that the earlier eruptions, which did deposit tephras in the lakes, must have been either especially voluminous, or southerly winds must have prevailed at the time of the eruption, or both.

scholarly journals A High-Resolution Geophysical Survey of Jenny Lake: Using Lake Sediments to Construct a Continuous Record of Tectonic Activity and Earthquake-Triggered Disturbances at Grand Teton National Park

2015 ◽  
Vol 38 ◽  
pp. 2-7
Author(s):  
Darren Larsen ◽  
Mark Abbot
Keyword(s):  
Lake Sediments ◽  
National Park ◽  
Sediment Cores ◽  
Tectonic Activity ◽  
Slope Failures ◽  
Grand Teton National Park ◽  
Field Investigations ◽  
History Of ◽  
Teton Range ◽  
Fault Scarps

The Teton Range, WY contains a legacy of late Cenozoic uplift and periodic Quaternary glaciations. Well-preserved fault scarps along the Teton fault displace glacier deposits from the most recent (Pinedale) glaciation and provide evidence for high fault activity during the past ~15,000 years. Observations of these scarps and previous field investigations indicate that postglacial fault offset occurred through a series of major, scarp-forming earthquakes. However, the postglacial paleoseismic record of the Teton fault remains incomplete. The goal of this project is to use lake sediments, contained in lake basins positioned on the fault, to construct a history of the timing and frequency of past earthquakes at Grand Teton National Park, and assess seismic impacts on diment erosion (e.g., landslides, debris flows, slope failures) and future hazard potential. Here, we report on multibeam sonar bathymetry and seismic reflection images from Jenny Lake, collected as part of an effort to identify glacial and tectonic landforms and to characterize infill stratigraphy. Our overarching objective is to combine these datasets with lake sediment cores from Jenny Lake and other nearby lakes to construct a continuous, accurately-dated record of past earthquakes and earthquake-generated slope failures in the Tetons.

The Holocene vegetation history of Isle Royale National Park, Michigan, U.S.A.

2003 ◽  
Vol 33 (6) ◽  
pp. 1144-1166 ◽  
Author(s):  
Robyn Flakne
Keyword(s):  
National Park ◽  
Vegetation History ◽  
Sediment Cores ◽  
Forest Composition ◽  
Isle Royale ◽  
Main Island ◽  
Isle Royale National Park ◽  
Forest Lake ◽  
History Of ◽  
Lake Ojibway

A vegetation history for Isle Royale National Park, Michigan, U.S.A., is reconstructed using pollen and spores extracted from two lake sediment cores. Lily Lake is on the southwestern end of the main island of Isle Royale surrounded by northern hardwoods forest. Lake Ojibway is on the northeastern end of the main island surrounded by boreal forest. Pollen and spore records were analyzed using pollen percentage diagrams, nonmetric multidimensional scaling ordination, and modern analog analysis. Squared chord distances for temporally paired subsamples from each site were calculated to determine palynological dissimilarities between the sites through time. These analyses revealed an overall vegetation history that is consistent with other regional reconstructions. High percentages of spruce pollen, indicating a cool climate, are present in the early Holocene, whereas high percentages of pine pollen, indicating a dry climate, occur in the mid-Holocene. The pollen records from the two sites diverge with increased precipitation during the late Holocene. At this time, birch-dominated forest is established near Lily Lake on till-derived soils. At Lake Ojibway, a mixed birch, pine, spruce, and fir forest is established on bedrock-derived soils. The divergence in forest composition is most pronounced within the last 500 years, and this divergence is tentatively attributed to the response of taxa on different substrates to increasing precipitation. Other possible explanations for the recent divergence include changing microclimates or disturbance regimes.

Radiocarbon ages of sorted circles on King George Island, South Shetland Islands, West Antarctica

2006 ◽  
Vol 18 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Gi Young Jeong
Keyword(s):  
Vegetation History ◽  
Sediment Cores ◽  
South Shetland Islands ◽  
King George Island ◽  
West Antarctica ◽  
Shetland Islands ◽  
Fine Grained ◽  
Plant Remains ◽  
Terrestrial Environments ◽  
History Of

Lichen and moss colonize the surface of glacial debris left after deglaciation. Transformation of unsorted debris into a sorted circle causes early plant remains to be preserved in the fine-grained centre encircled by a coarse, clastic border. Systematic radiocarbon dating of plant remains from the sorted stone circles on King George Island, South Shetland Islands, West Antarctica, yielded ages between 290–4710 14C yrs BP. The oldest age obtained from a large stone circle approximated the regional deglaciation age recorded in marine and lacustrine sediment cores. Most of the ages, however, underestimate the time of deglaciation due to the continual addition of younger plant remains, changes in soil motion, and the diverse vegetation history. Despite its current limitations as a terrestrial proxy for regional deglaciation, further systematic dating and careful interpretation based on surface processes may improve the usefulness of sorted circles in reconstructing the glacial and periglacial history of polar terrestrial environments.

From Competition to Cooperation: A History of Canada–US National Park Relations

2019 ◽  
Author(s):  
Terence Young ◽  
Alan MacEachern ◽  
Lary Dilsaver
Keyword(s):  
National Parks ◽  
National Park ◽  
The United States ◽  
The Us ◽  
Park Service ◽  
Settler Societies ◽  
History Of ◽  
Relationship Of ◽  
Flow Of Information ◽  
The Relationship

This essay explores the evolving international relationship of the two national park agencies that in 1968 began to offer joint training classes for protected-area managers from around the world. Within the British settler societies that dominated nineteenth century park-making, the United States’ National Park Service (NPS) and Canada’s National Parks Branch were the most closely linked and most frequently cooperative. Contrary to campfire myths and nationalist narratives, however, the relationship was not a one-way flow of information and motivation from the US to Canada. Indeed, the latter boasted a park bureaucracy before the NPS was established. The relationship of the two nations’ park leaders in the half century leading up to 1968 demonstrates the complexity of defining the influences on park management and its diffusion from one country to another.

Into Russian Nature

2020 ◽  
Author(s):  
Alan D. Roe
Keyword(s):  
World War Ii ◽  
Environmental Protection ◽  
National Parks ◽  
International Organizations ◽  
National Park ◽  
World War ◽  
Nature Protection ◽  
Soviet Government ◽  
History Of ◽  
Development Goals

Into Russian Nature examines the history of the Russian national park movement. Russian biologists and geographers had been intrigued with the idea of establishing national parks before the Great October Revolution but pushed the Soviet government successfully to establish nature reserves (zapovedniki) during the USSR’s first decades. However, as the state pushed scientists to make zapovedniki more “useful” during the 1930s, some of the system’s staunchest defenders started supporting tourism in them. In the decades after World War II, the USSR experienced a tourism boom and faced a chronic shortage of tourism facilities. Also during these years, Soviet scientists took active part in Western-dominated international environmental protection organizations, where they became more familiar with national parks. In turn, they enthusiastically promoted parks for the USSR as a means to reconcile environmental protection and economic development goals, bring international respect to Soviet nature protection efforts, and help instill a love for the country’s nature and a desire to protect it in Russian/Soviet citizens. By the late 1980s, their supporters pushed transformative, and in some cases quixotic, park proposals. At the same time, national park opponents presented them as an unaffordable luxury during a time of economic struggle, especially after the USSR’s collapse. Despite unprecedented collaboration with international organizations, Russian national parks received little governmental support as they became mired in land-use conflicts with local populations. While the history of Russia’s national parks illustrates a bold attempt at reform, the state’s failure’s to support them has left Russian park supporters deeply disillusioned.

Gendered Places and Depositional Histories: Reconstructing a Menstrual Lodge in the Interior Northwest

2019 ◽  
Vol 84 (3) ◽  
pp. 400-419 ◽  
Author(s):  
Molly Carney ◽  
Jade d'Alpoim Guedes ◽  
Kevin J. Lyons ◽  
Melissa Goodman Elgar
Keyword(s):  
Low Temperature ◽  
Pacific Northwest ◽  
Thin Section ◽  
Archaeological Record ◽  
Columbia Plateau ◽  
The North ◽  
Plant Remains ◽  
History Of ◽  
Experimental Firing ◽  
River Inundation

This project considered the deposition history of a burned structure located on the Kalispel Tribe of Indians ancestral lands at the Flying Goose site in northeastern Washington. Excavation of the structure revealed stratified deposits that do not conform to established Columbia Plateau architectural types. The small size, location, and absence of artifacts lead us to hypothesize that this site was once a non-domestic structure. We tested this hypothesis with paleoethnobotanical, bulk geoarchaeological, thin section, and experimental firing data to deduce the structural remains and the post-occupation sequence. The structure burned at a relatively low temperature, was buried soon afterward with imported rubified sediment, and was exposed to seasonal river inundation. Subsequently, a second fire consumed a unique assemblage of plant remains. Drawing on recent approaches to structured deposition and historic processes, we incorporate ethnography to argue that this structure was a menstrual lodge. These structures are common in ethnographic descriptions, although no menstrual lodges have been positively identified in the archaeological record of the North American Pacific Northwest. This interpretation is important to understanding the development and time depth of gendered practices of Interior Northwest groups.

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

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