Stratigraphic evidence for anthropogenically induced coastal environmental change from Oaxaca, Mexico

2005 ◽  
Vol 63 (3) ◽  
pp. 250-260 ◽  
Author(s):  
Michelle Goman ◽  
Arthur Joyce ◽  
Raymond Mueller
Keyword(s):  
Late Holocene ◽  
Environmental Changes ◽  
Drainage Basin ◽  
Sediment Cores ◽  
Human Populations ◽  
Archaeological Research ◽  
Barrier Formation ◽  
Valley Of Oaxaca ◽  
Major Hurricane ◽  
Hurricane Activity

Previous interdisciplinary paleoenvironmental and archaeological research along the Río Verde Valley of Oaxaca, Mexico, showed that Holocene erosion in the highland valleys of the upper drainage basin triggered geomorphic changes in the river's coastal floodplain. This article uses stratigraphic data from sediment cores extracted from Laguna Pastoría, an estuary in the lower Río Verde Valley, to examine changes in coastal geomorphology potentially triggered by highland erosion. Coastal lagoon sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late Holocene times. Three distinct storm facies are identified from sediment cores obtained from Laguna Pastoría, which indicate that profound coastal environmental changes occurred within the region and are correlated with increased sediment supplied from highland erosion. The Chione/Laevicardium facies was deposited in an open bay while the Mytella/barnacle facies and sand facies were deposited in an enclosed lagoon following bay barrier formation. We argue that highland erosion triggered major geomorphic changes in the lowlands including bay barrier formation by ∼2500 cal yr B.P. These environmental changes may have had significant effects on human populations in the region. The lagoon stratigraphy further indicates an increase in mid–late Holocene hurricane activity, possibly caused by increased El Niño frequencies.

scholarly journals Human Niche Construction and Population Growth in Pre-Columbian Amazonia

2017 ◽  
Author(s):  
Manuel Arroyo-Kalin
Keyword(s):  
Population Growth ◽  
Late Holocene ◽  
Niche Construction ◽  
Human Populations ◽  
Archaeological Research ◽  
Environmental Alteration ◽  
Human Niche Construction ◽  
Continued Use ◽  
Research Demands ◽  
Landscape Legacies

The use of Niche Construction Theory in archaeological research demands that we establish empirically how human-constructed niches acted as legacies that shaped the selection pressures affecting past human populations. One potential approach is to examine whether human demography changed as a result of the continued use of landscapes enduringly transformed by past societies. This paper presents proxies for Amazonian population growth during the late Holocene and discusses their significance within the broader context of landscape legacies resulting from cumulative anthropic environmental alteration during pre-Columbian times.

scholarly journals INFLUENCIA DEL RÍO ATRATO EN EL GOLFO DE URABÁ DURANTE EL HOLOCENO TARDÍO, MAR CARIBE COLOMBIANO

2016 ◽  
Vol 45 (1) ◽  
Author(s):  
Camilo Vélez Agudelo ◽  
Néstor Aguirre Ramírez
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Anthropogenic Factors ◽  
Northwestern Margin ◽  
Hydrodynamic Processes ◽  
Delta Progradation ◽  
Del Rio ◽  
Northern Branch

Sedimentary, geochemical (total organic carbon TOC, total nitrogen TN, total phosphorus TP, biogenic silica BSi and calcium carbonate (CaCO3) and diatoms data of two sediment cores were used to infer general environmental changes in the northern Gulf of Urabá during the late Holocene. The age models (AMS 14C ) suggested that core of the northeastern margin (SP 9) belong to ~960 years BP, while in the core of the northwestern margin (SP 41) the model was adjusted for the last ~2845 years BP. The results indicated that drilling sites are affected by different hydrodynamic processes that, in general, have been maintained during the late Holocene. While in the northwestern margin oceanic processes dominate and there is low input of fluvial sediments to this site, in the northeastern margin there are processes that favor the transport and accumulation of terrigenous sediments, which limit the growth of diatoms. Between 2845 and 2489 year BP, a higher sea level and wet conditions were recorded in the gulf. Since ~2445 years BP a gradual decrease in sea level allowed delta progradation towards the eastern side of the gulf. Apparently, this process would have intensified its presence in the last ~200 year BP, due to natural and anthropogenic factors. Even though the river discharges are channeled predominantly towards the east side of the Gulf, the trend of increasing TOC and diatoms data suggested fluvial input to the northwestern margin from ~800 years BP, which may be associated with a higher activity of Tarenas mouth, the northern branch of the Atrato River.

scholarly journals Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro delta, Spain

2017 ◽  
Author(s):  
Jaap H. Nienhuis ◽  
Andrew D. Ashton ◽  
Albert J. Kettner ◽  
Liviu Giosan
Keyword(s):  
Late Holocene ◽  
Large Scale ◽  
Environmental Changes ◽  
Drainage Basin ◽  
Wave Climate ◽  
Sediment Supply ◽  
Ebro Delta ◽  
Coarse Grained ◽  
Plan View ◽  
Numerical Model Experiments

Abstract. The distinctive plan-view shape of the Ebro Delta, Spain, reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and many other deltas represent autogenic (internal) dynamics or allogenic (external) forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes that affected the Ebro delta over the late Holocene. Based on numerical model experiments and the preserved and modern Ebro delta shape, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring a large increase (doubling) in coarse-grained fluvial sediment supply to the delta. We do not find evidence that changes in wave climate aided this delta expansion. River profile models suggest that such an instantaneous and sustained increase in coarse-grained, beach-compatible sediment to the delta would require a combination of flood discharge increase and increased sediment input into the river channel from upstream drainage basin erosion. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic signal of sediment supply and flooding intensity. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change and allowing a better understanding of the future of deltaic landforms.

PALEOLIMNOLOGY OF THE MAYA LOWLANDS

2002 ◽  
Vol 13 (1) ◽  
pp. 141-157 ◽  
Author(s):  
Mark Brenner ◽  
Michael F. Rosenmeier ◽  
David A. Hodell ◽  
Jason H. Curtis
Keyword(s):  
Late Holocene ◽  
Environmental Changes ◽  
Anthropogenic Activities ◽  
Yucatan Peninsula ◽  
Sediment Cores ◽  
Maya Lowlands ◽  
Holocene Climate ◽  
The Past ◽  
Yucatán Peninsula ◽  
Paleoclimate Records

Since the late 1950s, scientists have used sediment cores from lakes on the Yucatan Peninsula to explore the complex interactions among climate, environment, and ancient Maya culture. Early paleolimnological studies generally assumed that late Holocene climate was invariable. Consequently, paleolimnologically inferred environmental changes that occurred during the past 3,000 years or so—for example, forest decline and soil erosion—were attributed wholly to anthropogenic activities such as land clearance for agriculture and construction. Recent high-resolution, proxy-based paleoclimate records from continental and insular sites around the Caribbean Sea contradict the assumption of late Holocene climate stability. Instead, these core data suggest that regional drying began about 3,000 years ago and that the past three millennia were characterized by variable moisture availability. Paleoclimate inferences from Lakes Chichancanab and Punta Laguna, northern Yucatan Peninsula, indicate that drought events over the past 2,600 years were cyclical. These dry events, thought to have been driven by solar forcing, appear to have occurred approximately every two centuries (about 208 years). The driest period of the late Holocene occurred between A.D. 800 and 1000, coincident with the Classic Maya Collapse. We review the history of paleolimnological studies in the Maya Lowlands, discuss the difficulty of differentiating climatic signals from anthropogenic signals in late Holocene lake sediment profiles, and assess current understanding of past climate changes in the region based on regional lacustrine sediment studies.

scholarly journals Changes in climate, ocean and ice-sheet conditions in the Ross embayment, Antarctica, at 6 ka

1998 ◽  
Vol 27 ◽  
pp. 305-310 ◽  
Author(s):  
Eric J. Steig ◽  
Charles P. Hart ◽  
James W. C. White ◽  
Wendy L. Cunningham ◽  
Mathew D. Davis ◽  
...  
Keyword(s):  
Sea Ice ◽  
Late Holocene ◽  
Environmental Changes ◽  
Ross Sea ◽  
Ice Core ◽  
Sediment Cores ◽  
Methanesulfonic Acid ◽  
Ice Shelf ◽  
Radiocarbon Dates ◽  
Ice Shelves

Evidence from the Ross embayment, Antarctica, suggests an abrupt cooling and a concomitant increase in sea-ice cover at about 6000 BP (6 ka). Stable-isotope (δD) concentrations in the Taylor Dome ice core, at the western edge of the Ross embayment, decline rapidly after 6 ka, and continue to decline through the late Holocene. Methanesulfonic acid concentrations at Taylor Dome show opposite trends to δD Sediment cores from the western Ross Sea show a percentage minimum for the sea-ice diatom Fragilariopsis curta between 9 and 6 ka, whenTaylor Dome δD values are highest, followed by an increase through the late Holocene. Radiocarbon dates from raised beach deposits indicate that the retreat of ice shelves in the Ross embayment ceased at about 6 ka, coincident with the environmental changes inferred from the sediment and ice-core records. The similarity in timing suggests an important role for climate in controlling the evolution of ice-shelf margins following the end of the last glaciation.

scholarly journals Environmental changes, climate and anthropogenic impact in southern-eastern Tunisia during the last 8 kyr

2016 ◽  
Author(s):  
Sahbi Jaouadi ◽  
Vincent Lebreton ◽  
Viviane Bout-Roumazeilles ◽  
Giuseppe Siani ◽  
Rached Lakhdar ◽  
...  
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Environmental Changes ◽  
Climatic Variability ◽  
Classical Antiquity ◽  
Human Populations ◽  
Desert Ecosystems ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean

Abstract. Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) traces the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the Mid- to Late Holocene transition, between 8 and 3 ka, a succession of five wet/dry oscillations is recorded. An intense arid event occurs between 5.7 and 4.6 ka. This episode marks the onset of a long-term aridification trend with a progressive retreat of Mediterranean woody xerophytic vegetation and of grass steppes. It ends with the establishment of pre-desert ecosystems around 3 ka. The millennial-scale climate change recorded in the data from Sebkha Boujmel is consistent with records from the south and east Mediterranean, as well as with climatic records from the desert region for the end of the African Humid Period (AHP). Eight centennial climatic events are recorded at Sebkha Boujmel and these are contemporary with those recorded in the Mediterranean and in the Sahara. They indicate a clear coupling between the southern Mediterranean and the Sahara before 3 ka. The event at 4.2 ka is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic Cooling events is clearer from 3 ka onwards. These variations indicate the importance of climatic determinism in the structuring of landscapes, with the establishment of the arid climatic conditions of the Late Holocene. It is only from 3 ka onwards that the dynamic of plant associations is modified by both human activity and climatic variability. The climatic episodes identified during the historic period indicate strong regionalisation related to the differential impact of the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) on the Mediterranean basin. The local human impact on regional ecosystems is recorded in the form of episodes of intensification of pastoral and/or agricultural activities. The development of olive production and of several taxa associated with agriculture attest to increasing sedentism among human populations during Classical Antiquity. The significant increase in Artemisia (wormwood) between 1.1 and 0.8 ka (850–1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete re-shaping of the landscape is recorded during the 20th century. The remarkable expansion of the olive tree, and the deterioration of regional ecosystems with the spread of desert species, is linked to recent local socio-economic changes in Tunisia.

Late Quaternary Stratigraphic Charcoal Records from Madagascar

1987 ◽  
Vol 28 (2) ◽  
pp. 274-280 ◽  
Author(s):  
David A. Burney
Keyword(s):  
Late Holocene ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Time Of Arrival ◽  
Large Mammals ◽  
Human Settlement ◽  
Human Use ◽  
Anthropogenic Fires ◽  
Natural Component

AbstractThe classic view regarding the cause of the extinction of at least 17 species of large mammals, birds, and reptiles in Madagascar during the late Holocene implicates human use of fire to modify the environment. However, analysis of the charcoal stratigraphy of three sediment cores from Madagascar shows that late Pleistocene and early- to mid-Holocene sediments deposited prior to human settlement often contain more charcoal than postsettlement and modern sediments. This observation, which is confirmed by independent measurements from direct assay and palynological counting techniques, suggests that widely held but previously untested beliefs concerning the importance of anthropogenic fires in late Holocene environmental changes and megafaunal extinctions of Madagascar may be based on an overly simplified version of actual prehistoric conditions. Moderate to low charcoal values characterized only the late Holocene millennia immediately prior to the presumed time of arrival of the first settlers. Human settlement is probably indicated in the stratigraphy by the sharp rise in charcoal content observed beginning ca. 1500 yr B.P. Fire appears to be a significant natural component of prehuman environments in Madagascar, but some factor, probably climate, has modulated the extent of natural burning.

scholarly journals Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

2017 ◽  
Vol 5 (3) ◽  
pp. 585-603 ◽  
Author(s):  
Jaap H. Nienhuis ◽  
Andrew D. Ashton ◽  
Albert J. Kettner ◽  
Liviu Giosan
Keyword(s):  
Late Holocene ◽  
Large Scale ◽  
Environmental Changes ◽  
Drainage Basin ◽  
Wave Climate ◽  
Sediment Supply ◽  
Ebro Delta ◽  
Coarse Grained ◽  
Plan View ◽  
The North

Abstract. The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal) dynamics or allogenic (external) forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

scholarly journals Environmental changes, climate and anthropogenic impact in south-east Tunisia during the last 8 kyr

2016 ◽  
Vol 12 (6) ◽  
pp. 1339-1359 ◽  
Author(s):  
Sahbi Jaouadi ◽  
Vincent Lebreton ◽  
Viviane Bout-Roumazeilles ◽  
Giuseppe Siani ◽  
Rached Lakhdar ◽  
...  
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Environmental Changes ◽  
Climatic Variability ◽  
Classical Antiquity ◽  
Human Populations ◽  
Desert Ecosystems ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean

Abstract. Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) trace the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the mid- to late Holocene transition, between ca. 8 and 3 ka BP, a succession of five wet–dry oscillations is recorded. An intense arid event occurs between ca. 5.7 and 4.6 ka BP. This episode marks the onset of a long-term aridification trend with a progressive retreat of Mediterranean woody xerophytic vegetation and of grass steppes. It ends with the establishment of pre-desert ecosystems around 3 ka BP. The millennial-scale climate change recorded in the data from Sebkha Boujmel is consistent with records from the south and east Mediterranean, as well as with climatic records from the desert region for the end of the African Humid Period (AHP). Eight centennial climatic events are recorded at Sebkha Boujmel and these are contemporary with those recorded in the Mediterranean and in the Sahara. They indicate a clear coupling between the southern Mediterranean and the Sahara before 3 ka BP. The event at 4.2 ka BP is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic cooling events is clearer from ca. 3 ka BP onwards. These variations indicate the importance of climatic determinism in the structuring of landscapes, with the establishment of the arid climatic conditions of the late Holocene. It is only from ca. 3 ka BP onwards that the dynamic of plant associations is modified by both human activity and climatic variability. The climatic episodes identified during the historic period indicate strong regionalisation related to the differential impact of the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) on the Mediterranean Basin. The local human impact on regional ecosystems is recorded in the form of episodes of intensification of pastoral and/or agricultural activities. The development of olive production and of several taxa associated with agriculture attest to increasing sedentism among human populations during classical antiquity. The significant increase in Artemisia (wormwood) between ca. 1.1 and 0.8 ka BP (850–1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete reshaping of the landscape is recorded during the 20th century. The remarkable expansion of the olive tree, and the deterioration of regional ecosystems with the spread of desert species, is linked to recent local socio-economic changes in Tunisia.

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