Search results for "maar"

Maars of the Westeifel, Germany

2008

Within the Westeifel Volcanic Field 27% of the 250 Quaternary eruptive centers are maars. Maars form as a result of a highly explosive interactive process between rising melt and groundwater. In the Westeifel, probably thermal water plays an important role for the productive phreatomagmatic interaction process and, con-sequently, the high number of maars. The Westeifel maars show all transitions to scoria cones. Only the youngest maars are filled by a maar lake or a raised bog, and are well preserved. The older maars show a low diameter to depth ratio. Nearly one third of the Westeifel maars were formed during the Weichselian glaciation period. The isostatic movements during the increasing …

Numerical dating of the Eckfeld maar fossil site, Eifel, Germany: a calibration mark for the Eocene time scale.

2000

Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian. In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By 40Ar/39Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has been established. The Eckfeld basalt inverse isochron date of 44.3 +/- 0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary at 44 Ma and, together with the 1995 time scale of Berggren et al., a time…

Volcanic Lakes in Africa: The VOLADA_Africa 2.0 Database, and Implications for Volcanic Hazard

2021

Volcanic lakes pose specific hazards inherent to the presence of water: phreatic and phreatomagmatic eruptions, lahars, limnic gas bursts and dispersion of brines in the hydrological network. Here we introduce the updated, interactive and open-access database for African volcanic lakes, country by country. The previous database VOLADA (VOlcanic LAke DAta Base, Rouwet et al., Journal of Volcanology and Geothermal Research, 2014, 272, 78–97) reported 96 volcanic lakes for Africa. This number is now revised and established at 220, converting VOLADA_Africa 2.0 in the most comprehensive resource for African volcanic lakes: 81 in Uganda, 37 in Kenya, 33 in Cameroon, 28 in Madagascar, 19 in Ethiop…

Eckfeld Maar: Window into an Eocene Terrestrial Habitat in Central Europe

2010

: To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010, we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research. This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota. To date, nearly 250 papers and books have been published since the start of our project An up-to-date list of these publications can be found at http://www.eckfeldermaar.de.

27. A new holsteinian pollen record from the dry maar at Döttingen (Eifel)

2007

Abstract A new interglacial pollen sequence from the Dottingen dry maar in the Eifel region of the Rheinish Schield is presented. Palynology is used to correlate with several classical north German Holsteinian sites. The lake sediments reveal the complete interglacial and also 60 m of laminated sediments from the glacial preceding the Holsteinian. The interglacial section indicates limnic conditions in its lower part and telmatic conditions in its upper part with an intermediate episode of peat formation. Ash layers document intensive volcanism during the interglacial in the Eifel region. Some of the north German Holsteinian sites reveal spikes of high abundance of Pinus, Betula and Poaceae…

La intervención de Cenicienta en la construcción de las pirámides. Un tipo iconográfico en la primera serie litográfica de las Maravillas del mundo

2020

En el siglo XVI se realiza la primera serie de litografías de las Maravillas del mundo. En ellas se representan las arquitecturas más emblemáticas de la Antigüedad. Pero en la relativa a las pirámides de Egipto se esconde un tipo iconográfico que pasa desapercibido si no se conocen las fuentes historiográficas griegas. Alude a Rhodopis, la primera Cenicienta, y su papel clave en la construcción de las pirámides. Maarten Van Heemskerck y Philips Galle nos guían hasta los historiadores clásicos Heródoto y Estrabón a través de la iconografía, para hacernos conocedores de la historia de la joven Rhodopis, una joven griega cuyo zapato toma un águila y deja caer en el regazo del faraón egipcio. D…

"Kaikkivaltias vielä yhdesti valona" : metonymian ja metaforan rajankäynnin ongelmia

2006

Gas hazard assessment at the Monticchio crater lakes of Mt. Vulture, a volcano in Southern Italy

2009

Geochemical investigations have shown that there is a considerable inflow of gas into both crater lakes of Monticchio, Southern Italy. These lakes are located in two maars that formed 140 000 years ago during Mt. Vulture volcanos last eruptive activity. Isotopic analyses suggest that CO2 and helium are of magmatic origin; the latter displays 3 He ⁄ 4 He isotope ratios similar to those measured in olivines of the maar ejecta. In spite of the fact that the amount of dissolved gases in the water is less than that found in Lake Nyos (Cameroon), both the results obtained and the historical reports studied indicate that these crater lakes could be highly hazardous sites, even though they are loca…

Kirjoituksia eletyistä ja kerrotuista elämistä

2020


 
 
 Maarit Leskelä-Kärki: Toisten elämät: Kirjoituksia elämäkerroista. Helsinki: Avain, 2017, 272 s.
 
 

Memory-Based Mismatch Response to Frequency Changes in Rats

2011

Any occasional changes in the acoustic environment are of potential importance for survival. In humans, the preattentive detection of such changes generates the mismatch negativity (MMN) component of event-related brain potentials. MMN is elicited to rare changes (‘deviants’) in a series of otherwise regularly repeating stimuli (‘standards’). Deviant stimuli are detected on the basis of a neural comparison process between the input from the current stimulus and the sensory memory trace of the standard stimuli. It is, however, unclear to what extent animals show a similar comparison process in response to auditory changes. To resolve this issue, epidural potentials were recorded above the pr…