melišče / scree (Talus)

Melišče (talus) je zbiralnik oz. nanos kamnitega drobirja ob vznožju skalne stene ali strmega pobočja. Je z vegetacijo neporaslo pobočje z nakloni 26° do 42°. Nastane s kopičenjem kamnitega drobirja, ki zaradi mehaničnega preperevanja kamnin in nestabilnega zemljišča pada s sten. Na melišča vplivajo vremenski pogoji, sestava kamnin, vpad skladov in voda. Kjer je proces kopičenja drobira počasen ali prekinjen nastane fosilno melišče, ki se laho zaraste z vegetacijo.

Melišča se nanašajo na sipek derobir in manjše skale na pobočju. Talus, soroden izraz, je pobočje z večjimi skalami in balvani. Kjer je velika stenovitost, so ugodni pogoji za nastanek melišč. Nagnjenost pobočja mora biti takšna, da se na njem zadrži drobir oz. gruščnati material.

Mehanično razpadanje: material se odstranjuje s pobočij s hudourniškim odnašanjem in s samim vplivom deževnice in snežnice. Veliko temperaturno nihanja povzroča temperaturno preperevanje (zlasti zmrzal). Veter (eolsko delovanje) raznaša preperele delce, na premikanje pa vpliva tudi živi svet (obiskovalci, divjad).

Kemično preperevanje: na karbonatni grušč vpliva kemično raztapljanje (korozija) in odplavljanje karbonatov.

Tipi melišč:

• Podstensko melišče: zbira odpadlo kamenje, grušč na spodnjem robu je debelejši. Naklon med 29° in 33°.
• Podžlebno melišče: manjši naklon, bolj raznoliko. Nastaja s pomočjo plazov in hudournikov v žlebovih.

Viri: D. Kladnik (1981), I. Gams (Proteus 53), A. G. Brody et al. (2015).

A scree (talus) is a collector or deposit of crushed stone at the foot of a rock wall or steep slope. It is an unvegetated slope with inclinations of 26° to 42°. It is formed by the accumulation of stone rubble, which falls from the walls due to mechanical weathering. Scree is affected by weather conditions, rock composition, and water. Where the process of debris accumulation is slow or interrupted, a fossil scree is formed, often overgrown with vegetation.

Scree refers to loose debris and smaller rocks, while talus is associated with larger rocks and boulders. Favorable conditions exist where large rock walls are present. The slope of the scree depends on the angle of the underlying base.

Mechanical disintegration: material is removed by torrential drift and the influence of rainwater/snowmelt. Frost action is a major accelerator in rock cracking. Wind (aeolian action) and biological factors (wildlife and hikers) also contribute to material movement and sorting.

Chemical weathering: carbonate aggregates are affected by chemical dissolution (corrosion) and leaching.

Types:

• Sub-wall scree: accumulation of fallen stones with characteristic embankment slopes (29°-33°).
• Sub-channel scree: more varied, formed by winter avalanches and spring torrents in gullies.

Active screes are generally devoid of vegetation, whereas "fossil" screes are stabilized by plants.