scholarly journals Multiple Dating of a Long Flowstone Profile

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 503-509 ◽  
Author(s):  
Mebus A Geyh ◽  
G J Hennig
Keyword(s):  
Growth Rate ◽  
West Germany ◽  
Spin Resonance ◽  
Dating Methods ◽  
Growth History ◽  
Order Of Magnitude ◽  
History Of ◽  
Dating Method ◽  
Closed Systems ◽  
Glacial Periods

Dense speleothem samples are considered as closed systems and are, therefore, possibilities for any dating method. Four dating methods (14C, U/Th, paleomagnetism, and electron spin resonance = ESR) were used for samples up to 1,000,000 yr old and taken along a vertical flowstone profile in the Heggen cave in West Germany. Also δ18O and δ13C analyses were carried out.The reliability of the results of each method is dependent on the diagenetic processes that took place during the complex growth history of the flowstone. Speleothem growth was interrupted during glacial periods. During interglacial periods, at least the stalagmite growth rate was greater by one order of magnitude than during interstadial periods. During the periods of low interstadial growth rate various processes might have changed the 14C, 18O, and 13C concentrations, leaching might have removed uranium, recrystallization might have moved thorium several centimeters, and increased content of radon in the cave might have exaggerated the accumulated dose (AD) at the speleothem surface. As a result, 14C ages may be too small and U/Th as well as ESR data may be too large.

Paleogene to Quaternary geodynamical evolution of the lowland Central Amazonia inferred by weathering phases dating

2020 ◽  
Author(s):  
Cecile Gautheron ◽  
Cristiana Cabriolu ◽  
Fabiano Pupim ◽  
Mauricio Parra ◽  
Stéphane Schwartz ◽  
...  
Keyword(s):  
Amazon River ◽  
Fluvial Terraces ◽  
Left Margin ◽  
Stratigraphic Framework ◽  
Dating Methods ◽  
Central Amazonia ◽  
History Of ◽  
Dating Method ◽  
Past Conditions ◽  
Lowland Amazonia

<p>The landscape in lowland Amazonia is shaped by large rivers, whose depositional-erosive dynamics built fluvial terraces covered by upland forests. Thus, fluvial deposits distributed across lowland Amazonia are of crucial relevance since they represent the best accessible archives to study the history of environment and climate change. The timing of the assembly of the modern transcontinental Amazon River is considered a key event in the landscape evolution of Amazonia, however, proposed ages range from Miocene, early Pliocene to Pliocene/Pleistocene. Therefore, regional stratigraphic correlations need to improve to ensure a better understanding of reconstructions of past conditions in Amazonia during the Cenozoic. Yet, these are difficult due to the lack of absolute ages to constrain phases of sediment deposition or erosion and weathering. In lowland central Amazonia, past environmental conditions are recorded in the Alter do Chão and Novo Remanso Formations. Both units are dominated by sandy and highly oxidized sediments with scarce paleontological remains complicating the application of biostratigraphy dating methods. The Alter do Chão and Novo Remanso Formations are well exposed in the left margin of the Solimões-Amazon River main stem and show remarkable zones rich in supergene iron weathering products, which has been used to define the stratigraphic boundaries among the Alter do Chão Formation, Novo Remanso Formation and overlying sediments. In this study, we use the (U-Th-Sm)/He dating method on goethite and hematite grains to determine the age of iron-enrichment layers and duricrusts that mark boundary surfaces used to define the stratigraphic framework of the Alter do Chão and Novo Remanso formations. The (U-Th-Sm)/He ages allow to improve chronological constraints for both formations and to discuss the timing of fluvial terraces building and weathering conditions in central Amazonia through time.</p>

Growth Patterns in Sand Lance, Ammodytes dubius, from the Grand Bank

1981 ◽  
Vol 38 (7) ◽  
pp. 841-846 ◽  
Author(s):  
G. H. Winters
Keyword(s):  
Growth Rate ◽  
Standard Deviation ◽  
Growth Patterns ◽  
Sand Lance ◽  
Apparent Change ◽  
Growth Compensation ◽  
Growth History ◽  
History Of ◽  
Back Calculation

Growth patterns in sand lance (Ammodytes dubius) from the Grand Bank were examined using back-calculated lengths from otolith measurements. Lee's phenomenon of apparent change in growth rate with age is clearly demonstrated as is the phenomenon of growth compensation. Lee's phenomenon is explained by discriminatory mortality of the faster-growing sand lance whereas growth compensation is attributed to the differing ages of maturity of the initial faster-growing and slower-growing fish. The significant reduction in the standard deviation and the increasing degree of left skewness in length frequencies of older sand lance is explained by a combination of Lee's phenomenon and growth compensation acting together throughout the growth history of individual sand lance.Key words: sand lance, growth, back-calculation. Grand Bank

Growth history of a Neotropical tree inferred from the spacing of leaf scars

1993 ◽  
Vol 9 (4) ◽  
pp. 525-532 ◽  
Author(s):  
David A. King
Keyword(s):  
Growth Rate ◽  
Height Growth ◽  
Mature Trees ◽  
Lowland Forest ◽  
Neotropical Tree ◽  
Growth History ◽  
Rate Class ◽  
History Of ◽  
Highly Correlated ◽  
Passage Times

ABSTRACTThe Neotropical tree, Pourouma aspera (Cecropiaceae), supports large lobed leaves on an erect stem which seldom branches below a height of 5 m. The prominent leaf scars are visible on trunks of mature trees and the distance between scars is highly correlated with the height growth rate when the leaves were produced. Relationships between height growth rate, internode length and light environment were determined from marked P. aspera saplings in a tropical wet lowland forest and used to infer the past growth histories of larger saplings and trees. Inferred growth rates were quite variable, both within and between individuals. Estimated passage times to grow from 0.7 to 2.2 m tall ranged from 0.6–23 y, with a mean of 4.4 y (N = 61). The study illustrates the importance of examining the distribution of growth rate over the length of the stem in addition to the more usual distribution of numbers of individuals per growth rate class. Species such as Pourouma, which respond strongly to light, complete much of their total juvenile growth during intervals of high light, even though most saplings are growing slowly in shade at any given time.

scholarly journals Relative Dating of Moraines from the Arid Part of Altai: Applying of Rock Weathering and Colonization by Biota Data within the Framework of the Method

2021 ◽  
Author(s):  
Dmitrii A. Ganyushkin ◽  
Sofya N. Lesovaya ◽  
Dmitrii Y. Vlasov ◽  
Gennady P. Kopitsa ◽  
László Almásy ◽  
...  
Keyword(s):  
Biomass Accumulation ◽  
Rock Surface ◽  
Fine Earth ◽  
Fine Grained ◽  
Relative Dating ◽  
Initial Stage ◽  
Dating Methods ◽  
Rock Disintegration ◽  
History Of ◽  
Dating Method

For the Altai mountainous region, especially the arid south-eastern part, the history of glacier fluctuations in Pleistocene and Holocene is still poorly known. The key plots were located in the Kargy valley (2288-2387 m a. s. l.) that is not currently affected by glaciations. The relative dating method was applied to define Pleistocene moraine chronology and configuration in the Kargy valley. Taking into account that relative dating methods are primarily based on weathering pat-terns, the mineralogy, porosity, and specificity of biological colonization as an agent of weath-ering were obtained for the moraine samples. Three moraine groups of different age (presumably MIS 6, MIS 4, and MIS 2) were identifies based on detailed investigation of morphological features. The moraine age was indirectly confirmed by the mesostructure of the moraine samples repre-sented by fine-grained shale: the older sample is characterized by a more developed fractal sur-face than the younger one. The growth of biota (crustose lichen and micromycetes) leads to initial biomass accumulation and subsequent rock disintegration. The accumulation of autochthonous fine earth on the rock surface was considered the initial stage of fine earth formation affected by biota.

A Reflection on Crucial Periods in 50 Years of Social Psychology (in Germany)

2019 ◽  
Vol 50 (1) ◽  
pp. 1-6
Author(s):  
Katja Corcoran ◽  
Michael Häfner ◽  
Mathias Kauff ◽  
Stefan Stürmer
Keyword(s):  
Social Psychology ◽  
Early Development ◽  
West Germany ◽  
East And West Germany ◽  
The Future ◽  
History Of ◽  
East And West

Abstract. In this article, we reflect on 50 years of the journal Social Psychology. We interviewed colleagues who have witnessed the history of the journal. Based on these interviews, we identified three crucial periods in Social Psychology’s history, that are (a) the early development and further professionalization of the journal, (b) the reunification of East and West Germany, and (c) the internationalization of the journal and its transformation from the Zeitschrift für Sozialpsychologie to Social Psychology. We end our reflection with a discussion of changes that occurred during these periods and their implication for the future of our field.

German Angst

2020 ◽  
Author(s):  
Frank Biess
Keyword(s):  
Federal Republic ◽  
National Socialism ◽  
West Germany ◽  
Peace Movements ◽  
Original Analysis ◽  
The Holocaust ◽  
The Future ◽  
History Of ◽  
Fear And Anxiety ◽  
Relationship Of

German Angst analyzes the relationship of fear and democracy in postwar West Germany. While fear has historically been associated with authoritarian regimes, the book highlights the role of fear and anxiety in a democratizing society: these emotions undermined democracy and stabilized it at the same time. By taking seriously postwar Germans’ uncertainties about the future, the book challenges dominant linear and teleological narratives of postwar West German “success.” It highlights the prospective function of memories of war and defeat, of National Socialism and the Holocaust. Fears and anxieties derived from memories of a catastrophic past that postwar Germans projected into the future. Based on case studies from the 1940s to the present, the book provides a new interpretive synthesis of the Federal Republic. It tells the history of the Federal Republic as a series of recurring crises, in which specific fears and anxieties emerged, served a variety of political functions, and then again abated. Drawing on recent interdisciplinary insights of emotion studies, the book transcends the dichotomy of “reason” and “emotion.” Fear and anxiety were not exclusively irrational and dysfunctional but served important roles in postwar democracy. These emotions sensitized postwar Germans to the dangers of an authoritarian transformation, and they also served as the emotional engine of the environmental and peace movements. The book also provides an original analysis of the emotional basis of right-wing populism in Germany today, and it explores the possibilities of a democratic politics of emotion.

scholarly journals Is there enough star formation in simulated protoclusters?

2020 ◽  
Vol 501 (2) ◽  
pp. 1803-1822
Author(s):  
Seunghwan Lim ◽  
Douglas Scott ◽  
Arif Babul ◽  
David J Barnes ◽  
Scott T Kay ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Star Formation History ◽  
Test Case ◽  
Numerical Resolution ◽  
Formation History ◽  
Order Of Magnitude ◽  
History Of ◽  
Hydrodynamical Simulations ◽  
Formation Efficiency

ABSTRACT As progenitors of the most massive objects, protoclusters are key to tracing the evolution and star formation history of the Universe, and are responsible for ${\gtrsim }\, 20$ per cent of the cosmic star formation at $z\, {\gt }\, 2$. Using a combination of state-of-the-art hydrodynamical simulations and empirical models, we show that current galaxy formation models do not produce enough star formation in protoclusters to match observations. We find that the star formation rates (SFRs) predicted from the models are an order of magnitude lower than what is seen in observations, despite the relatively good agreement found for their mass-accretion histories, specifically that they lie on an evolutionary path to become Coma-like clusters at $z\, {\simeq }\, 0$. Using a well-studied protocluster core at $z\, {=}\, 4.3$ as a test case, we find that star formation efficiency of protocluster galaxies is higher than predicted by the models. We show that a large part of the discrepancy can be attributed to a dependence of SFR on the numerical resolution of the simulations, with a roughly factor of 3 drop in SFR when the spatial resolution decreases by a factor of 4. We also present predictions up to $z\, {\simeq }\, 7$. Compared to lower redshifts, we find that centrals (the most massive member galaxies) are more distinct from the other galaxies, while protocluster galaxies are less distinct from field galaxies. All these results suggest that, as a rare and extreme population at high z, protoclusters can help constrain galaxy formation models tuned to match the average population at $z\, {\simeq }\, 0$.

scholarly journals The ‘oldest dated document of the Cairo Genizah’ (Halper 331): The Seleucid era and sectarian Jewish calendars

2021 ◽  
pp. 1-18
Author(s):  
EVE KRAKOWSKI ◽  
SACHA STERN
Keyword(s):  
Near East ◽  
Early Medieval ◽  
Near Eastern ◽  
Dating Methods ◽  
Marriage Contract ◽  
History Of ◽  
Legal Document ◽  
Cairo Genizah ◽  
Medieval Egypt

Abstract Halper 331 is the fragment of a codex that has been styled the ‘oldest dated document of the Cairo Genizah’. It preserves the opening of a Jewish legal document dated to the year 1182 (Seleucid era), which appears to have been copied into this codex, probably as a formulary, not long after this date, in the late 9th century. In this article, the text of this fragment, in Aramaic and Hebrew, is edited, and its identification as the beginning of a marriage contract (ketubbah) is evaluated. Its Egyptian provenance is questioned, partly because the earliest evidence for the introduction of the Seleucid era by Jews in Egypt dates from the mid-10th century. The article surveys the history of Jewish dating methods in early medieval Egypt and the Near East, in an attempt to clarify this question. The specific date of the document deviates from the rabbinic calendar, but agrees with that of the contemporary Jewish Near Eastern sectarian groups of Abū ʿImrān al-Tiflīsī and Ismāʿīl al-ʿUkbarī; this document could thus uniquely attest one of these sectarian Jewish calendars.

scholarly journals A Study about the Temporal Constraints on the Martian Yardangs’ Development in Medusae Fossae Formation

2021 ◽  
Vol 13 (7) ◽  
pp. 1316
Author(s):  
Jia Liu ◽  
Zongyu Yue ◽  
Kaichang Di ◽  
Sheng Gou ◽  
Shengli Niu
Keyword(s):  
Size Distribution ◽  
Indirect Method ◽  
Common Method ◽  
Planetary Surface ◽  
Temporal Constraints ◽  
History Of Development ◽  
Long Duration ◽  
History Of ◽  
Dating Method

The age of Mars yardangs is significant in studying their development and the evolution of paleoclimate conditions. For planetary surface or landforms, a common method for dating is based on the frequency and size distribution of all the superposed craters after they are formed. However, there is usually a long duration for the yardangs’ formation, and they will alter the superposed craters, making it impossible to give a reliable dating result with the method. An indirect method by analyzing the ages of the superposed layered ejecta was devised in the research. First, the layered ejecta that are superposed on and not altered by the yardangs are identified and mapped. Then, the ages of the layered ejecta are derived according to the crater frequency and size distribution on them. These ages indicate that the yardangs ceased development by these times, and the ages are valuable for studying the evolution of the yardangs. This indirect dating method was applied to the areas of Martian yardangs in the Medusae Fossae Formation (MFF). The ages of the selected six layered ejecta range from ~0.50 Ga to ~1.5 Ga, indicating that the evolution of the corresponding yardangs had been ceased before these times. Analysis of more layered ejecta craters and superposed yardangs implies that yardangs in the MFF have a long history of development and some yardangs are still in active development.

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