scholarly journals Fluvial piracies in the NE sector of the Sierra de Aconquija (Tafí Valley, NW Argentina)

2020 ◽  
Vol 46 (1) ◽  
pp. 285-301 ◽  
Author(s):  
J.L. Peña-Monné ◽  
M.M. Sampietro-Vattuone

The Sierra de Aconquija is a recently uplifted mountain chain in NW Argentina. The NE side of the sierra is drained by the Muñoz and Los Alisos rivers – whose base level is the Las Carreras Depression that is located to the SW of the Tafí valley. Two of the major headwaters of the Muñoz River suffered during its Holocene development from piracy by the Los Alisos River. These piracies had important consequences on the size of both basins and the functioning of their alluvial fans. The main causes of the captures were changes in river dynamics during Lateglacial and Holocene glacial events. Neotectonic activation does not seem to be the most determining factor, although there are active Holocene faults nearby (Las Carreras Fault 2). Geomorphological and human occupation data recovered from the alluvial fans enables us to estimate that the most recent capture was produced during the Late Holocene.

The Holocene ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 244-261 ◽  
Author(s):  
Pablo G Messineo ◽  
Marcela S Tonello ◽  
Silvina Stutz ◽  
Alfonsina Tripaldi ◽  
Nahuel Scheifler ◽  
...  

The main objective of this work is to generate and integrate interpretations of human occupation strategies and inferences of the environmental-climatic conditions in the central Pampas during the middle and late Holocene. We present a novel archeological–geological–paleoecological analysis in the area of the Cabeza de Buey lake, placed in an aeolian landscape. During the middle Holocene, two events of human occupations were recognized at Laguna Cabeza de Buey 2 archeological site. Both events present a small amount of lithic materials, a low diversity of tools and activities developed with them (principally hard material), and the hunting and primary processing of artiodactyls. These evidences suggest a locus of specific activity associated with an ephemeral human settlement under climate conditions drier than present and the presence of small, brackish, and shallow water bodies. For the late late Holocene, the hunter-gatherer occupation has a higher depositional rate of lithic assemblage, stones with diverse origins, presence of pottery fragments, a great lithic tool diversity, knapping techniques, and activities developed with these tools (processing wood, bone, hide, non-woody plant, and soft material). These evidences reveal an occupation with a higher degree of recurrence represented by a locus of multiple activities associated with a more stable landscape, such as an environment of dunes fixed by grass vegetation, and the establishment of a permanent water body. The different environmental characteristics for the middle and late Holocene in this area promoted that human groups develop two different patterns of mobility, settlement and use of space.


The Holocene ◽  
2002 ◽  
Vol 12 (5) ◽  
pp. 569-584 ◽  
Author(s):  
M. Vermoere ◽  
S. Bottema ◽  
L. Vanhecke ◽  
M. Waelkens ◽  
E. Paulissen ◽  
...  

2017 ◽  
Vol 163 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Brianne Herrera ◽  
Daniel Peart ◽  
Nicole Hernandez ◽  
Kate Spradley ◽  
Mark Hubbe

Author(s):  
Martin Williams

This chapter provides an overview of the geography, hydrology, and climate of NE Africa, with particular reference to the complex interactions between river regime, climate, the biota, and human settlement. During the Early (11.7–8.2 ka) and Middle Holocene (8.2–4.2 ka) the climate was far less arid than today across the Nile basin, including Nubia, albeit with sporadic dry phases. Climatic desiccation set in during the Late Holocene (4.2 ka to present), with minor wet phases. Intervals when the Nile flow regime was apparently shifting from high to low flow and flood plain incision have provisional ages of ca. 8.15–7.75 ka, 6.4–6.15 ka, 5.7–5.45 ka, 4.7–4.25 ka, 3.35–2.9 ka, 2.8–2.55 ka, and 1600 ce. In the Kerma area of Nubia there were two periods of relatively dense human occupation in the earlier part of the Holocene from 10 ka to 8 ka and from 7 ka to 6 ka, with two significant gaps in the archaeological record at 7.5–7.1 ka and 6.0–5.4 ka, that coincided with very low levels in Lake Challa, a maar lake on the eastern flank of Mt Kilimanjaro, near the Ugandan headwaters of the White Nile.


2020 ◽  
Vol 236 ◽  
pp. 106265 ◽  
Author(s):  
Stephen E. Darby ◽  
Peter G. Langdon ◽  
James L. Best ◽  
Julian Leyland ◽  
Christopher R. Hackney ◽  
...  

2002 ◽  
Vol 62 (3) ◽  
pp. 375-385 ◽  
Author(s):  
C. J. R. ALHO ◽  
M. SCHNEIDER ◽  
L. A. VASCONCELLOS

The State Park of Ilha Grande is only a part (5,594 hectares) of the entire island (19,300 hectares) which is located off the south coast of Rio de Janeiro state, between the cities of Mangaratiba and Angra dos Reis. Approximately half of the Park area (47%) is covered by dense Atlantic forest. The secondary forest growth is in a process of ecological succession close to attaining maturity (43%) and the remaining part (10%) is composed of human-altered areas (1%), rocky outcrops with herbaceous vegetation (7%), mangroves and beaches (2%). The fauna is well represented but already shows signs of degradation with introduced species. The analysis of the degree of threat has shown that the dense forest habitat has a relatively stable status of conservation while the secondary forest, the mangrove and the herbaceous vegetation on rocky outcrops (and their fauna) are categorized as vulnerable. The area altered by human occupation is considered threatened. Since the coastal area where Ilha Grande is located is well known for its beautiful scenery (known as the green coast, because of the contrast between the ocean and the Atlantic forest covering the Serra do Mar mountain chain). There is a strong possibility for tourism to become the means in which to achieve economic sustainability for conservation. Contradictorily, tourism is also the major threat to local biodiversity and its landscape units. Because tourism is not organized and controlled, during high season the numbers grow above local capacity, giving rise to a proliferation of hotels, guesthouses and camping grounds. The resulting untreated open sewage, random garbage disposal and other harmful activities form the major threats to biodiversity.


2017 ◽  
Vol 89 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula A. Rodríguez-Zorro ◽  
Bruno Turcq ◽  
Renato C. Cordeiro ◽  
Luciane S. Moreira ◽  
Renata L. Costa ◽  
...  

AbstractLocated at the northwestern part of the Amazon basin, Rio Negro is the largest black-water river in the world and is one of the poorest studied regions of the Amazon lowlands. In the middle-upper part of the Rio Negro were retrieved sediment cores form Lake Acarabixi, which were analyzed using pollen, spores, charcoal, and geochemistry. The aim of this study was to detect the influences from humans and river dynamics on the vegetation history in the region. Two main periods of vegetation and river dynamics were detected. From 10,840 to 8240 cal yr BP, the river had a direct influence into the lake. The lake had a regional input of charcoal particles, which reflected the effect of the dry Holocene period in the basin. Furthermore, highland taxa such asHedyosmumandMyrsinewere found at that time along with igapó forest species that are characteristic to tolerate extended flooding likeEschweilera,Macrolobium, Myrtaceae,Swartzia, andAstrocaryum. During the late Holocene (1600 to 650 cal yr BP), more lacustrine phases were observed. There were no drastic changes in vegetation but the presence of pioneer species likeVismiaandCecropia, along with the signal of fires, which pointed to human disturbances.


Geomorphology ◽  
2014 ◽  
Vol 208 ◽  
pp. 225-237 ◽  
Author(s):  
Matthieu Ghilardi ◽  
David Psomiadis ◽  
Kosmas Pavlopoulos ◽  
Sylvie Müller Çelka ◽  
Sylvian Fachard ◽  
...  

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