Data on stratotypes of the neopleistocene-holocene regional and local subdivisions in the Caspian region

Considered in the work are data characterizing stratotypes of regional and local stratigraphic subdivisions, which are distinguished in the Neopleistocene-Holocene sedimentary succession of the Caspian region. The succession is composed of sediments deposited by the Caspian transgressions and intervening continental sediments of the late Quaternary. Except for stratotypes of the Tyurkyany Horizon and Gyurgyany Formation, which are established in borehole sections, the other ones represent the well-stratified natural sections accessible for examination of their subdivisions distinguished based on biostratigraphic criteria. Mollusks of the genus Didacna Eichwald and fossil assemblages of large mammals are used to substantiate stratigraphy of marine and terrestrial deposits, respectively.     

Evolution of a debris-rock slide causing a natural dam: the flash flood of Río Santa Cruz,Province of San Juan—November 12, 2005

Between 2001 and 2005, a large debris rock slide occurred on the western slope of the Cordillera de Santa Cruz in the southeast Andean corner of the Province of San Juan (31°40′ S–70°16′ W). The landslide material accumulated in a downstream gorge as a natural dam of the Santa Cruz river, forming a large-volume lake. In November 2005, probably as a result of the increasing pressure of the water volume, this natural dam breached off with a violent and unexpected flash flood. In addition to life-threatening instances lived by some people downstream, this flood caused great economic loss to main localities of the Department of Calingasta, as well as considerable damage to one of the most relevant projects of the Province, the Caracoles Hydropower Project dam on the San Juan river. Considering the high costs of any physical remediation for a natural dam located in this high, remote, and inaccessible mountain area with no reliable road access, the main protective measures left to be pondered are the installation of a flash-flood early-warning system connected to downstream localities, along with a program of hydrological monitoring at the dam-forming area and annual satellital monitoring to verify the evolution of accumulated mass movements.     

Morphometric analysis of Colangüil river basin and flash flood hazard,San Juan,Argentina

This work analyzes various morphometric characteristics of the Colangüil river basin in order to evaluate flash flood hazards. Such high-water events pose a risk to the similarly named small village located at the basin’s foot area. For this purpose, the basin is divided into seven sub-basins and some basic measurements (surface, perimeter, basin length, river beds, elevations and slope of the main river bed, and of a number of minor river beds) are calculated. These measurements permit to predict approximately the behavior of the basin in the presence of a series of theoretical rainstorms that may generate unusual runoff volumes that make up such flash floods.     

Defect distribution and dissolution morphologies on low-index surfaces of α-quartz

The dissolution of prismatic and rhombohedral quartz surfaces by KOH/H₂O solutions was investigated by atomic force microscopy. Rates of dissolution of different classes of surface features (e.g., steps, voids, and dislocation etch pits) were measured. The prismatic surface etched almost two orders of magnitude faster than the rhombohedral surface, mostly due to the difference in the number and the rate of dissolution of extended defects, such as dislocations. Because of the presence of imperfect twin boundaries, defect densities on the prismatic surface were estimated at 50-100 μm⁻², whereas the rhombohedral surface possessed only ∼0.5-1.0 μm⁻², mostly in the form of crystal voids. Crystal voids etched almost one order of magnitude faster on the prismatic surface than on the rhombohedral surface due to differences in the number and the density of steps formed by voids on the different surfaces. In the absence of extended defects, both surfaces underwent step-wise dissolution at similar rates. Average rates of step retreat were comparable on both surfaces (∼3-5 nm/h on the prismatic surface and ∼5-10 nm/h on the rhombohedral surface). Prolonged dissolution left the prismatic surface reshaped to a hill-and-valley morphology, whereas the rhombohedral surface dissolved to form coalescing arrays of oval-shaped etch pits.     

Paleohydrology of the Black Sea Pleistocene Basins

The history of the Black Sea Pleistocene basins, whose paleohydrologic and faunistic characteristics markedly differ, is discussed. A distinct hierarchy of rhythms is established in the variations in the levels of the water bodies.     

A relation between extreme daily precipitation and extreme short term precipitation

The Royal Netherlands Meteorological Institute (KNMI) has published the KNMI’06 climate scenarios in 2006. These scenarios give the possible states of the climate in The Netherlands for the next century. Projections of changes in precipitation were made for a time scale of 1 day. The urban drainage sector is, however, more interested in projections on shorter time scales. Specifically, time scales of 1 h or less. The aim of this research is to provide projections of precipitation at these shorter time scales based on the available daily scenarios. This involves an analysis of climate variables and their relations to precipitation at different time scales. On the basis of this analysis, one can determine a numeric factor to translate daily projections into shorter time scale projections.     

First results of investigation into the relation between magnetic properties of bottom sediments in the Northern Caspian and variations in the Caspian Sea level in the Late Neo-Pleistocene

The first data of investigation into the relation between changes in magnetic properties of the Northern Caspian sediments and variations in the Caspian Sea level in the Late Neo-Pleistocene are presented. It is shown that there is a certain correlation between magnetic characteristics of sediments and variations in the Caspian Sea level that cause changes in the lithological and faunistic composition of sediments.