Late Pleistocence dynamics in central Pennsylvania (USA) – new findings on periglacial slope deposits, pedology and chronology

2020 ◽  
Author(s):  
Florian Hirsch ◽  
Thomas Raab ◽  
Patrick Drohan ◽  
Alexander Bonhage
Keyword(s):  
Late Quaternary ◽  
Soil Formation ◽  
General Term ◽  
Plant Litter ◽  
Cold Climate ◽  
Central Pennsylvania ◽  
New Findings ◽  
The Us ◽  
Slope Deposits ◽  
Slope Direction

<p>Pleistocene dynamics are usually associated with the formation of characteristic landforms such as moraines, dunes, or kettle holes. However, cold climate processes can also shape the landscape but not result in such prominent relief features. This is especially true for slope deposits that have been formed in periglacial regions through geli-solifluction and/or cryoturbation.  While the terms used to refer to such slope deposits may differ with the disciplines of soil science and/or geomorphology, such features are often still recognized by practicing scientists. In the US, geli-solifluction and/or cryoturbation features are subsumed with a very general term ‘colluvium’ whereas in Europe a more sophisticated number of terms is used separating sediments which formed under cold climate processes from sediments which formed due to anthropogenic induced soil erosion. Our study focuses on the stratigraphy of late Quaternary deposits and the soil formation in the northern Appalachians. The study area wasn’t glaciated during the Wisconsin glaciation; hence no MIS 5 or younger glacial deposits are reported.</p><p>To advance a common terminology between geoscientist, we examined pedons representative of Holocene and periglacial dynamics that reflect the strong role that solifluction played in pre and MIS 5landscape dynamics. Especially on foot slopes and toe slopes pedon stratigraphy is characterized by a several meter-thick par-autochthonous deposits that are rich in clasts. Clasts in deposits are aligned with the slope direction and are imbricated; on back slopes par-autochthonous deposits are also present but more shallow. Stratigraphy and OSL chronology strongly suggests that during the late Pleistocene several phases of morphodynamics shaped the landscape via solifluction followed by an eolian input of silt to the soils/sediments. Geochemistry reflects the multi-layer character of the soil profiles showing clear differences between the bedrock and deposits above. Elevated values of manganese in the surface soil indicate the importance of plant litter biocylcing during the Holocene. Hence on a landscape scale, the distribution of soils and the pedogenesis is strongly related to the par-autochthonous character of the substrate rather than the bedrock.</p>

Late Pleistocene and Holocene Paleoenvironments of Chalco Lake, Central Mexico

1993 ◽  
Vol 40 (3) ◽  
pp. 332-342 ◽  
Author(s):  
Maria Socorro Lozano-Garcı́a ◽  
Beatriz Ortega-Guerrero ◽  
Margarita Caballero-Miranda ◽  
Jaime Urrutia-Fucugauchi
Keyword(s):  
Volcanic Activity ◽  
Lake Level ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Cold Climate ◽  
Central Mexico ◽  
Pollen Record ◽  
Loss On Ignition ◽  
Southeastern Part ◽  
Saline Marsh

AbstractIn order to establish paleoenvironmental conditions during the late Quaternary, four cores from the Basin of Mexico (central Mexico) were drilled in Chalco Lake, located in the southeastern part of the basin. The upper 8 m of two parallel cores were studied, using paleomagnetic, loss-on-ignition, pollen, and diatom analyses. Based on 11 14C ages, the analyzed record spans the last 19,000 14C yr B.P. Volcanic activity has affected microfossil abundances, both directly and indirectly, resulting in absence or reduction of pollen and diatom assemblages. Important volcanic activity took place between 19,000 and 15,000 yr B.P. when the lake was a shallow alkaline marsh and an increase of grassland pollen suggests a dry, cold climate. During this interval, abrupt environmental changes with increasing moisture occurred. From 15,000 until 12,500 yr B.P. the lake level increased and the pollen indicates wetter conditions. The highest lake level is registered from 12,500 to ca. 9000 yr B.P. The end of the Pleistocene is characterized by an increase in humidity. From 9000 until ca. 3000 yr B.P. Chalco Lake was a saline marsh and the pollen record indicates warmer conditions. After 3000 yr B.P. the lake level increased and human disturbance dominates the lacustrine record.

Principal operators' farm risk attitudes in hot and cold climates

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahmad Zia Wahdat ◽  
Michael Gunderson
Keyword(s):  
Risk Mitigation ◽  
Risk Attitude ◽  
Cold Climate ◽  
Risk Attitudes ◽  
Ordered Logit ◽  
Climate Classification ◽  
Content Type ◽  
Hot Climate ◽  
The Us ◽  
The Government

PurposeThe study investigates whether there is an association between climate types and farm risk attitudes of principal operators.Design/methodology/approachThe study exploits temperature variation in the diverse climate types across the US and defines hot- and cold-climate states. Ordered logit and generalized ordered logit models are used to model principal operators' farm risk attitudes, which are measured on a Likert scale. The study uses two datasets. The first dataset is a 2017 survey of US large commercial producers (LCPs). The second dataset provides a Köppen-Geiger climate classification of the US at a spatial resolution of 5 arcmin for a 25-year period (1986–2010).FindingsThe study finds that principal operators in hot-climate states are 4–5% more likely to have a higher willingness to take farm risk compared to principal operators in cold-climate states.Research limitations/implicationsIt is likely that farm risk mitigation decisions differ between hot- and cold-climate states. For instance, the authors show that corn acres' enrollment in federal crop insurance and computers' usage for farm business are pursued more intensely in cold-climate states than in hot-climate states. A differentiation of farm risk attitude by hot- and cold-climate states may help agribusiness, the government and economists in their farm product offerings, farm risk management programs and agricultural finance models, respectively.Originality/valueBased on Köppen-Geiger climate classification, the study introduces hot- and cold-climate concepts to understand the relationship between climate types and principal operators' farm risk attitudes.

scholarly journals Dating of Holocene Stratigraphy with Soluble and Insoluble Organic Fractions at the Lubbock Lake Archaeological Site, Texas: An Ideal Case Study

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 473-485 ◽  
Author(s):  
Herbert Haas ◽  
Vance Holliday ◽  
Robert Stuckenrath
Keyword(s):  
Late Quaternary ◽  
Soil Formation ◽  
Archaeological Site ◽  
High Plains ◽  
Buried Soils ◽  
Marsh Sediments ◽  
Organic Fractions ◽  
Holocene Stratigraphy ◽  
Lake Site

The Lubbock Lake site, on the Southern High Plains of Texas, contains one of the most complete and best-dated late Quaternary records in North America. A total of 11714C dates arc available from the site, determined by the Smithsonian and SMU Laboratories. Of these dates, 84 have been derived from residues (humin) and humates (humic acids) of organic-rich marsh sediments and A horizons of buried soils. Most of the ages are consistent with dates determined on charcoal and wood, and with the archaeologic and stratigraphic record. The dates on the marsh sediments are approximate points in time. Dates from the top of buried A-horizons are a maximum for burial and in many cases are close to the actual age of burial. Dates from the base of the A-horizons are a minimum for the beginning of soil formation, in some cases as much as several thousand years younger than the initiation of pedogenesis. A few pairs of dates were obtained from humin and humic acid derived from split samples; there are no consistencies in similarities or differences in these age pairs. It also became apparent that dates determined on samples from scraped trench walls or excavations that were left open for several years are younger than dates from samples taken from exactly the same locations when the sampling surfaces were freshly excavated.

Late Quaternary aggradation and incision in the headwaters of the Yangtze River, eastern Tibetan Plateau, China

2021 ◽  
Author(s):  
Yang Yu ◽  
Xianyan Wang ◽  
Shuangwen Yi ◽  
Xiaodong Miao ◽  
Jef Vandenberghe ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Yangtze River ◽  
Late Quaternary ◽  
Cold Climate ◽  
Luminescence Dating ◽  
Tectonic Activity ◽  
The Yangtze River ◽  
Eastern Tibetan Plateau ◽  
Sedimentary Process ◽  
Fluvial Terraces

River aggradation or incision at different spatial-temporal scales are governed by tectonics, climate change, and surface processes which all adjust the ratio of sediment load to transport capacity of a channel. But how the river responds to differential tectonic and extreme climate events in a catchment is still poorly understood. Here, we address this issue by reconstructing the distribution, ages, and sedimentary process of fluvial terraces in a tectonically active area and monsoonal environment in the headwaters of the Yangtze River in the eastern Tibetan Plateau, China. Field observations, topographic analyses, and optically stimulated luminescence dating reveal a remarkable fluvial aggradation, followed by terrace formations at elevations of 55−62 m (T7), 42−46 m (T6), 38 m (T5), 22−36 m (T4), 18 m (T3), 12−16 m (T2), and 2−6 m (T1) above the present floodplain. Gravelly fluvial accumulation more than 62 m thick has been dated prior to 24−19 ka. It is regarded as a response to cold climate during the last glacial maximum. Subsequently, the strong monsoon precipitation contributed to cycles of rapid incision and lateral erosion, expressed as cut-in-fill terraces. The correlation of terraces suggests that specific tectonic activity controls the spatial scale and geomorphic characteristics of the terraces, while climate fluctuations determine the valley filling, river incision and terrace formation. Debris and colluvial sediments are frequently interbedded in fluvial sediment sequences, illustrating the episodic, short-timescale blocking of the channel ca. 20 ka. This indicates the potential impact of extreme events on geomorphic evolution in rugged terrain.

Age and significance of slope deposits, Black Mountain, Canberra

Soil Research ◽  
1973 ◽  
Vol 11 (1) ◽  
pp. 13 ◽  
Author(s):  
AB Costin ◽  
HA Polach
Keyword(s):  
Snow Cover ◽  
Cold Climate ◽  
Tree Cover ◽  
Soil Conditions ◽  
Climate Conditions ◽  
Slope Deposits ◽  
The Mean ◽  
Carbonized Wood ◽  
Black Mountain ◽  
Lake George

Extensive slope deposits are described from Black Mountain, Canberra, with particular reference to a profile exposed in an excavation at 590 m on the lower eastern slopes of the mountain. Buried organomineral soil materials near the base of the slope deposits contain fragments of carbonized wood with an average age of 27,800 (+2500, - 1900) years B.P. This age is not significantly different from the mean age of 26,790 � 810 years B.P. for carbonized wood in slope deposits near Lake George, and is close to the mean age of 31,500 � 1000 years B.P. for slope deposits above 1000 m in the Snowy Mountains. A method for comparing the results of carbon-14 determinations is described. The Snowy Mountains deposits indicated a periglacial climate with mean annual temperatures at least 8-10�C lower than at present. On the basis of their similar appearance and age, it is suggested that the Black Mountain deposits were also formed under cold-climate conditions. If this were so, the synchronous slope deposits near Lake George (and river terraces and slope deposits in an upland tributary of the Shoalhaven River) must also have developed during a colder climate. The climatic and associated soil conditions considered necessary for the formation of periglacial deposits at Black Mountain are discussed. Estimates of the lowering in temperature (compared with present-day temperature) which would have been involved vary from a crude estimate of about 14�C (annual) with relatively high precipitations and prolonged snow cover, to a more conservative estimate of 9�C (winter), 11�C (summer), and 10�C (annual) if the winter precipitations and snow cover were light. Even under the latter conditions, tree cover would have been minimal or absent from the tableland environment.

scholarly journals Combination of Numerical Dating Techniques Using 10Be in Rock Boulders and 14C of Resilient Soil Organic Matter for Reconstructing the Chronology of Glacial and Periglacial Processes in a High Alpine Catchment during the Late Pleistocene and Early Holocene

Radiocarbon ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 537-552 ◽  
Author(s):  
Filippo Favilli ◽  
Markus Egli ◽  
Dagmar Brandova ◽  
Susan Ivy-Ochs ◽  
Peter W Kubik ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Late Quaternary ◽  
Chemical Characterization ◽  
Soil Formation ◽  
Parent Material ◽  
Surface Dynamics ◽  
Exposure Dating ◽  
Minimum Age ◽  
Absolute Dating

Glacier fluctuations and paleoclimatic oscillations during the Late Quaternary in Val di Rabbi (Trentino, northern Italy) were reconstructed using a combination of absolute dating techniques (14C and 10Be) and soil chemical characterization. Extraction and dating of the stable fraction of soil organic matter (SOM) gave valuable information about the minimum age of soil formation and contributed to the deciphering of geomorphic surface dynamics. The comparison of 10Be surface exposure dating (SED) of rock surfaces with the 14C ages of resilient (resistant to H2O2 oxidation) soil organic matter gave a fairly good agreement, but with some questionable aspects. It is concluded that, applied with adequate carefulness, dating of SOM with 14C might be a useful tool in reconstructing landscape history in high Alpine areas with siliceous parent material. The combination of 14C dating of SOM with SED with cosmogenic 10Be (on moraines and erratic boulders) indicated that deglaciation processes in Val di Rabbi were already ongoing by around 14,000 cal BP at an altitude of 2300 m asl and that glacier oscillations might have affected the higher part of the region until about 9000 cal BP. 10Be and 14C ages correlate well with the altitude of the sampling sites and with the established Lateglacial chronology.

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