Wyniki wyszukiwania - BazTech

1

Weathering rind age assignment of Neoglacial deposits in the Okstindan Mountains, northern Norway

Mahaney W. C.

Studia Quaternaria

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2016

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Vol. 33, Nr 2

131--138

EN

Previous soil stratigraphic analysis of soil morphogenesis in the Okstindan Mountains established a Late Neoglacial soil evolutionary sequence based on historically monitored and radiocarbon-dated moraine positions over the last ~3.0 cal yr BP. Thus pedon evolution ranged from C/Cu®Ah/Cox/Cu®pedostratigraphic succession of Ah/C/Cu/Lb/ Cub/Ahb/Coxb/Cub profiles with a maximum rind weathering time of ~1.0 kyr. Following successive retreat phases of Neoglacial ice, weathering rind development continued apace on moraines, each rind population recording weathering time following successive glacier stillstands. The age of the youngest deposits falls within the period 1900–1910 AD, or the last 100 yrs, with variable moraine positions all documented by historical depictions of the position of the Austre Okstindan glacial lobe prior retreating to its present position. The next older group of deposits is considered to have been emplaced near the end of the LIA or around ~1800 AD, with time of rind development set at 200 yr, possibly older. The oldest moraine set within the late Neoglacial sequence lies atop a pedostratigraphic column, the uppermost soil radiocarbon dated at ~1.0 yr BP. Given the range of mean rind development across this threshold of deposits, from 0.22 ±0.03 mm in the inner group, 0.66 ±0.07mm in the middle group, to 1.38 ±0.15 mm in the outer, older group, it is clear that finite measurements at several sites within a suite of deposits, some dated by radiocarbon, can evenly discriminate between deposits in a glacial succession.

2

Radiocarbon dating of fossil bats from Dobšina Ice Cave (Slovakia) and potential palaeoclimatic implications

Gradziński M., Hercman H., Peresviet-Soltan A., Zelinka J., Jelonek M.

Annales Societatis Geologorum Poloniae

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2016

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Vol. 86, No. 3

341--350

EN

Although Dobšina Ice Cave (DIC, Carpathians, Slovakia) is located outside the high-mountain area, it hosts one of the most extensive blocks of perennial subterranean ice, the volume of which is estimated at more than 110,000 m3. Frozen bat remains were found in the lowermost part of the perennial ice block. They belong to Myotis blythii (Tomes) and the M. mystacinus morpho-group. The radiocarbon dating of bat soft tissues yielded ages of 1266–1074 cal. yr BP and 1173–969 cal. yr BP. The undetermined bat, found in the same part of the ice section in 2002, was previously dated at 1178–988 cal. yr BP (Clausen et al., 2007). The dates testify that the ice crystallized at the turn of the Dark Ages Cold Period and the Medieval Warm Period. The calculated accumulation rate of cave ice varies between 0.7 cm/year and 1.4 cm/year at that time, and is similar to the present ice accumulation rate in DIC. Constant crystallization of ice during the Medieval Warm Period is hypothesized to reflect dry summer seasons since the supply of relatively warm water in the summer is one of the key factors causing the erosion of cave ice. The uppermost sample was covered with 20.6 m of ice. Between ca 1065 cal. yr BP and the present day, the ice grew faster than between ca 1210 yr BP and ca 1065 yr BP by a factor of 1.3–1.8. This may have resulted from conditions favourable for ice accumulation during the Little Ice Age.

3

A palaeotemperature record for the Finnish Lakeland based on microdensitometric variations in tree rings

Helama S., Vartiainen M., Holopainen J., Mäkelä H. M., Kolström T., Meriläinen J.

Geochronometria

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2014

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Vol. 41, no. 3

265--277

EN

X-ray based tree-ring data of maximum latewood densities (MXD) was combined for south-eastern Finland. This data originated from subfossil and modern pine (Pinus sylvestris L.) materials comprising a continuous dendroclimatic record over the past millennium. Calibrating and verifying the MXD chronologies against the instrumental temperature data showed a promising opportunity to reconstruct warm-season (May through September) temperature variability. A new palaeotemperature record correlated statistically significantly with the long instrumental temperature records in the region and adjacent areas since the 1740s. Comparisons with tree-ring based (MXD and tree-ring width) reconstructions from northern Fennoscandia and northern Finland exhibited consistent summer temperature variations through the Medieval Climate Anomaly, Little Ice Age, and the 20th century warmth. A culmination of the LIA cooling during the early 18th century appeared consistently with the Maunder Minimum, when the solar activity was drastically reduced. A number of coolest reconstructed events between AD 1407 and 1902 were coeval to years of crop failure and famine as documented in the agro-historical chronicles. Results indicate an encouraging possibility of warm-season temperature reconstructions using middle/south boreal tree-ring archives to detail and enhance the understanding of past interactions between humans, ecosystems and the earth.

4

Wiek wałów morenowych we wschodniej części przedpola lodowca Fláa (SE Islandia) w oparciu o wyniki datowania lichenometrycznego

Łuszczak K., Modzelewska A., Sawicka D., Niezabitowska D., Dąbski M.

Landform Analysis

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2013

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Vol. 24

45--54

PL

Wyniki datowania lichenometrycznego trzech wałów morenowych położonych we wschodniej części przedpola lodowca Fláa zostały opracowane w oparciu o pomiary plech Rhizocarpon przy zastosowaniu: i) analizy gradientu rozkładu częstości populacji (GSF), ii) metody największej plechy (LL), iii) metody średniej z pięciu największych plech oraz (5LL) iv) metody pojedynczej przewidywanej plechy (1-IN-1000). Stwierdzono, że maksymalny zasięg lodowca Fláa w małej epoce lodowej przypada na przełom XIX i XX w. Ponadto wykazano niejednorodne tempo recesji czoła lodowca w obrębie jednego lobu oraz wyraźny wpływ warunków mikrośrodowiskowych na liczebność porostów i tempo ich wzrostu.

EN

The results of lichenometric dating of Fláajökull moraine ridges located in the eastern part of its marginal zone have been carried out on the base of measurements of the Rhizocarpon thalli and using analyses of: i) the size-frequency distribution gradient (GSF), ii) the largest lichen (LL), iii) the five largest lichens (5LL), and iv) “1-IN-1000” method. It was found that the maximum extent of the glacier in the Little Ice Age occurred at the turn of 19th and 20th centuries. Moreover, the results indicate that the glacier recession rate was not consistent in all parts of the snout and that micro-environmental conditions significantly influence lichen populations and the lichen growth rate.

5

Warunki klimatyczne okresu średniowiecza a powstanie, rozwój i upadek grodziska na Zawodziu w Kaliszu

Hildebrandt-Radke I.

Landform Analysis

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2011

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Vol. 16

69-72

EN

The early medieval stronghold in Kalisz was established in the ninth century among the branches of meandering Prosna river. The stronghold's castle was located on the floodplain terrace of Prosna river at an altitude of 100-108 m asl. In the tenth and eleventh centuries numerous redevelopments within the town occurred. In the early thirteenth century, as a result of fightings among dukes, the stronghold was exposed to destruction. Long-term flooding (1221-1223) resulted in the change of the main Prosna river channel. Prosna no longer assured the settlement with defensive functions. The above, and subsequent invasion of duke Henry I the Bearded (Henryk Brodaty) on Zawodzie in 1233, determined moving the castle on a fluvial terrace, in today's center of Kalisz.

6

The first dating of Cave Ice from the Tatra Mountains, Poland and its implication to palaeoclimate reconstructions

Hercman H., Gąsiorowski M., Gradziński M., Kicińska D.

Geochronometria

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2010

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Vol. 36

31-38

EN

Lodowa Cave in Ciemniak, which belongs to the dynamic ice cave type, contains the biggest perennial block of cave-ice in the Tatra Mountains. The ice represents congelation type, since it originates from freezing of water which infiltrates the cave. Two generations of ice have been recognized in this cave. They are divided by the distinct unconformity. The ice building both generations is layered. Two moths which were found in the younger generations were sampled and dated by 14C method yielding 195 ± 30 and 125 ± 30 years. Bearing in mind the position in the section and the fact that the cave ice has waned since the 20s of the last century, the age is 1720-1820 AD and 1660-1790 AD respectively. It proves that the ice was formed during the Little Ice Age. Hence, the erosion boundary which underlies this generation records the degradation of ice before the Little Ice Age most probably during the Medieval Warm Period. The ice volume in the cave was substantially smaller before the Little Ice Age than it is today, despite the clear tendency to melting, which has been recognized since 20s of the last century. The older generation of ice is supposed to have its origins in a cold stage between the Atlantic period and the Medieval Warm Period.

7

Klimat Arktyki w późnym glacjale i holocenie

Marsz A. A.

Problemy Klimatologii Polarnej

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2009

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nr 19

33-79

PL

Praca referuje wyniki badań nad zmianami klimatycznymi w Arktyce, jakie zachodziły od początku późnego glacjału do momentu rozpoczęcia obserwacji instrumentalnych. Większą uwagę skupiono na zmianach klimatycznych, jakie miały miejsce w ciągu ostatnich 2500 lat. Zwrócono również uwagę na synchro-niczność zmian klimatycznych w Arktyce i wyraźnie rysujące się związki między zwiększonym dopływem wód atlantyckich do Arktyki, a kolejnymi fazami ociepleń.

EN

This work presents an overview of literature devoted to presenting the results of research into climatic changes in the Arctic noted from the beginning of Late Glacial up to the moment when instrumental observation started. Greater emphasis was put on climatic changes which occurred during last 2000-2500 years. It was noted that the climatic changes in the Arctic were synchronical, that the rate of changes from the cooler seasons to the warmer ones and in the other way was fast and that the correlations between the increased import of the Atlantic waters to the Arctic and the following phases of warming were clear. The final part presented how the intensity of the Atlantic waters inflow influences the way the ice cover controls the mechanism of climatic changes in the Arctic.

8

Changes in relief of the Azau Valley in Central Caucasus Mts resulting from impact of volcanic activity and glaciers' oscillations during the last 1100 years

Łajczak A.

Landform Analysis

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2009

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Vol. 11

40-59

EN

I analysed changes in the relief of the partly glaciated Azau Valley in the Central Caucasus, neighbouring to Elbrus volcanic cone (5643m a.s.l.) resulting from intensification of volcanic activity and valley glaciers’ oscillations during the last 1100 years. Field research, analysis of topographic maps and photographs from the last 140 years as well as information in literature were the basis for my work. I identified the most important geomorphological processes modelling the valley: a lava flow, floods of jökulhlaup type, glaciers’ transgressions and recessions, erosion of moraines and mass movements on the slopes. I distinguished eight sections of the Azau Valley varied in their relief and being under the differentiated influence of the listed geomorphological processes. The valley under question, represents the Alpine type area of typical cascade like transfer of waste material from the slope to the valley systems and further along its floor. Hanging tributary valleys on the Azau Valley slopes are valleys exporting waste material while the main valley functions as the valley importing waste material. In the period of absence of visible volcanic activity of Elbrus, the fastest changes in the Azau Valley relief take place during the recession of the valley and slope glaciers and of ice cap on this volcano. Findings proof interdependence of intensity of material aggradation in the valley and the amount of moraine deposits which can quickly erode and be transported to the stream channel, easily accessible weathered material derived from marginal ice-free areas as well as on the volume of ice melting water discharging great loads of sediment.

9

An attempt to assess the modern and the Little Ice Age climatic snowline altitude in the Tatra Mountains

Zasadni J., Kłapyta P.

Landform Analysis

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2009

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Vol. 10

124-133

EN

An empirical glacio-climatic relation (Ohmura et al., 1992) and meteorological data (temperature and precipitation) are employed to provide the elevation in the Tatra Mts. climate model, where conditions are suitable for hypothetical glacierisation (temperature-precipitation ELA). During the Little Ice Age (LIA) it is to have been 1.5 centigrade colder than during the warmest decades of the 20th century (Niedźwiedź, 2004); however, some scenarios are used to define precipitation amounts related to the vertical distribution in climate model and temporal variability. The results indicate that during both considered periods - the warmest decades of the 20th century and the coolest period of LIA - the climatic snowline (cSL) was placed in most cases above the highest Tatra Mts. summits and crests. However, its spatial arrangement was unequal. In the vicinity of Kasprowy Wierch, the modern cSL is assessed to be at ca. 2,450-2,650 m a.s.l. and that during LIA at ca. 2,300-2,450 m a.s.l. In the case of Lomnicky Štit (2,634 m) it was at the level of ca. 2,700–2,800 m a.s.l. (modern times) and ca. 2,600–2,700 m a.s.l. (LIA). The discrepancies in the cSL altitude between these two locations can be explained in part by exposition to the prevailing moisture transport and orographically-induced precipitation.

10

Environmental changes in the central Baltic Sea during the past 1000 years: inferences from sedimentary records, hydrography and climate

Leipe T., Dippner J.W., Hille S., Voss M., Christiansen C., Bartholdy J.

Oceanologia

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2008

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No. 50 (1)

23-41

EN

Short sediment cores from the eastern Gotland Basin were investigated using a multi-proxy approach in order to reconstruct the environmental conditions of the area during the past 1000 years. Sediment data and facies were discussed in relation to hydrographic features (salinity, oxygen) and climate change. During the medieval warm period (MWP), from about 900 to 1250 AD, the hydrographic and environmental conditions were similar to those of the present time (modern warm period, since about 1850): a temporally stable halocline, caused by regular saline water inflows from the North Sea, prevents vertical mixing and leads to bottom water anoxia and the deposition of laminated, organic-rich sapropels. During the period from about 1250 to 1850, referred to as the cold phase (including the Little Ice Age), the environmental conditions of the central Baltic Sea were distinctly different: the lower salinity, resulting from reduced North Sea water inflows, allowed vertical convection of the water column and long-term stable ventilation of the sea bed (oxic stage). Both the productivity of the planktonic ecosystem as well as the preservation of organic matter in the sediments improved during the warm periods. The anthropogenic impact can be identified within the recent laminated sequence by a temporal reconstruction of pollutant deposition. Our findings imply a climate-change driven shift in the environmental conditions and the ecosystem of the Baltic from the north to the south and back to the north.

11

Analiza dendrogeomorfologiczna ruchów masowych na obszarze polskich Karpat fliszowych

Krąpiec M., Margielewski W.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2000

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T. 26, z. 2

141-171

PL

W obrębie Karpat fliszowych wydatowano okresy aktywizacji 23 osuwisk. Do analizy wykorzystano zaproponowaną przez autorów analizę par krzywych dendrochronologicznych drzew porastających analizowane osuwiska. Sygnały diagnostyczne dla uruchamiania podłoża, uzyskiwano zestawiając krzywe dendrochronologiczne odstokowych i dostokowych partii pnia tego samego drzewa. Zliczanie uśrednionych sygnałów dla okresów 5 letnich, pozwoliło na wykreślenie krzywej aktywizacji poszczególnych form osuwiskowych i pasm górskich, a także Karpat zachodnich. Analiza przebiegu tej krzywej wskazuje na korelację jej maksimów z powodziami i nawalnymi deszczami oraz wstrząsami sejsmicznymi, szczególnie tymi związanymi z końcem małej epoki lodowej

EN

Periods of activity of 23 landslides in the area of the Polish Flysch Carpathians, were dated with the dendrochronological method. The research was performed with a new, proposed by the authors, method of analysis of pairs of tree-ring patterns of trees growing on the landslide areas. The analysed pairs of dendrochronological curves, representing upper and lower sides of trunks of inclined trees overgrowing the investigated landslides, yielded signals diagnostic for the ground movements. These diagnostic signals, averaged for successive five-years' periods, were used for construction of activity curves for individual landslides, for mountain ranges, the Western Flysch Carpathians. Analysis of shapes of these curves demonstrated high correlation of its maxima with the floods, heavy rainstorms and earthquakes, particularly those related to the Little Ice Age