Podrobnosti záznamu

Název
    Gravity and orientated pressure as factors controlling "honeycomb weathering" of the Cretaceous castellated sandstones (northern Bohemia, Czech Republic)
Údaj o odpovědnosti
    Radek Mikuláš
Autor
    Mikuláš, Radek
Jazyk
    anglicky
Zdrojový dokument - seriál
    Věstník Českého geologického ústavu (Bulletin of the Czech Geological Survey)
Svazek/č.
    Vol. 76, no. 4
Strany
    p. 217-226
Rok
    2001
Poznámky
    5 obr., 2 pl., 25 bibl.
    il.
    Zkr. název ser.: Věst. Čes. geol. Úst. (Bull. Czech geol. Surv.)
Předmětová skupina
    česká křídová pánev
    eroze
    křída-svrchní
    pískovce
    reliéf
    tlak
    zvětrávání chemické
Geografické jméno
    ČR-Čechy
Klíčové slovo
    Bohemia
    Castellated
    Controlling
    Cretaceous
    Czech
    Factors
    Gravity
    Honeycomb
    Northern
    Orientated
    Pressure
    Republic
    Sandstones
    Weathering
Abstrakt (anglicky)
   A thorough, "sophisticated" geometry of honeycomb surfaces suggests that not only processes froming the pits but also some "construction plan" has to be involved. Lateral sides of rock arches often bear honeycombs having axes parallel to the curve of the arch vault thus copying a presumed pressure vector (lines of force). Most of the pits are spindle-shaped or cullular but some are arcuate with rudimentary oblique bottoms. Cellular honeycombs are characteristically developed on vaults of spherical or parabolic rock shelters and abri. These show similar parameters as the previous group but their axes are usually close to the projection of vertical line onto the wall. Therefore, it is difficult to assess whether the vector of gravity or the vector of pressume is responsible. Surfaces of fallen blocks bear pits of double or triple shape.
   1, symmetrical arcuate ones with flat bottoms; 2, symmetrical arcuate ones with oblique bottoms and oblique axes; the obliqueness, however, is presumably caused by the rock fall and not by the irregulal growth; 3, "reconstructed" honeycombs, usually larger than the two previous types; their upper parts are inclined and somewhat asymmetrical, bottoms are flat. Some blocks bear only the "reconstructed" honeycombs. The examples show that the bottom is "re-built" more rapidly than the vault, and consequently, bottoms or arcuate honeycombs are the place of the maximum loss of the sandstone. The fact that a rock crust usually does not harden horizontal or sub-horizontal surfaces may be one of the reasons
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    4. 7. 2007
Datum importu
    8. 8. 2012