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  • Author: Piotr Migoń x
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Pre-Quaternary geomorphological history and geoheritage of Britain

Substantial parts of the British Isles preserve landscapes that are the legacy of pre-Quaternary times. Some of these may be the result of burial and exhumation of pre-Cenozoic features. However, most landscapes post-date the Cretaceous transgression during which a Chalk mantle was laid down. Much of the British Isles became land during the Palaeogene and the Chalk cover was rapidly removed over large areas. Sea floor spre-ading, thermal uplift, and intrusion and extrusion of igneous material occurred. Landscapes also evolved in response to warm climatic conditions and this may have led to etchplanation. In the Neogene various surface formed and were affected by ongoing tectonic activity. Various estimates have been made of Cenozoic denu-dation rates and amounts, but they appear to have varied spatially and temporally. Landscapes which provide tangible evidence of pre-Quaternary times include those of north-east Scotland and southern England. Such ancient landscapes are important components of the Geoheritage of Britain.

Abstract

In the desert environment of south-west Jordan thick sequences of continental sandstones of Cambrian-Ordovician age support spectacular scenery, comparable with that of the Colorado Plateau of south-west USA or the central Sahara and similar in many aspects to the Danxia landform of southern China. Dissection of a sandstone tableland has given rise to numerous inselbergs and large mesas, rising from the sand-covered desert floor. The height of the hills varies from a few tens to 500-700 m in the Wadi Rum area, whereas their slope shapes are controlled by lithological properties of particular sandstone units. Rock walls of the sandstone inselbergs are subject to frequent rock falls and rock slides and host an impressive array of tafoni and honeycombs due to selective weathering, as well as a number of rock arches. Lithological differences within the sandstone sequence are crucial controls on the shape and evolution of rock slopes, exerting the influence via contrasting patterns of weathering and slope failures. The presence of ferruginous layers in the Umm ‘Ishrin Sandstone is of major importance and explains the fundamental morphological differences between the otherwise similar Umm ‘Ishrin and Disi sandstone units

Abstract

Applied research in geomorphology includes landform analysis and evaluation from a specific perspective of scientific significance and global relevance. In this paper, landform diversity of Seoraksan, Republic of Korea, a UNESCO World Heritage candidate, is compared with geomorphic characteristics of two World Heritage properties in China, Huangshan and Sanqingshan. Seoraksan represents an almost complete mountain geomorphic system of considerable contemporary dynamics, with outstanding scenery and spectacular landforms such as domes, fins, bedrock channels, waterfalls, and inherited block fields. It is argued that Seoraksan contains outstanding scientific and aesthetic values, not present at the Chinese properties, offering scope for successful nomination.

Abstract

A characteristic feature of sandstone-capped escarpments in the Stołowe Mountains is the occurrence of extensive boulder mantles which extend from the rock face to the footslope over distances of 300–500 m. The hypothesis implying rockfall as the process of boulder release from the rock face and subsequent transport is tested by means of Conefall 1.0 software, designed to simulate run-out zones of rockfalls. The actual extent of boulder mantles is much larger than the simulated extent, which casts doubt on the applicability of rockfall scenario. Alternative hypotheses are briefly discussed and it is concluded that a similar morphological effect can be achieved by in situ caprock disintegration and sub-caprock slope lowering and retreat.

Abstract

We found ubiquitous evidence of ongoing slope instability by analysing the variability of tree-ring eccentricity index in trees growing on three apparently relict landslide slopes in the Sudetes (Poland, Central Europe). Slow movement of these landslide bodies occurs in the present-day conditions and is recorded almost every year, although with variable intensity. Correlation of dendrochronological record with the rainfall record from a nearby station in Mieroszów for the 1977–2007 period is very poor for two deep-seated rotational slides at Mt Suchawa and Mt Turzyna but considerably better for a shallow flowslide at Mt Garbatka. While this may reflect higher permeability of heavily jointed rocks involved in deep-seated sliding this could be linked with imperfections in the rainfall record. Dendrochronology proved capable of detecting minor displacements within landslides which otherwise show no geomorphic evidence of recent activity. Therefore, claims for the entirely relict nature of the landslides are not substantiated.