Piotr Migoń and Andrew Goudie
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.
Piotr Migoń and Andrew Goudie
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
Piotr Migoń, Kyung-Sik Woo and Marek Kasprzak
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.
Ireneusz Malik, Małgorzata Wistuba, Piotr Migoń and Maria Fajer
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.
Filip Duszyński, Piotr Migoń and Mateusz Czesław Strzelecki
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.
Łukasz Pawlik, Łukasz Musielok, Piotr Migoń, Dominika Wrońska-Wałach, Filip Duszyński and Marek Kasprzak
The historical dimension of pit-and-mound topography has been studied at the Mt Rogowa Kopa locality, Stołowe Mountains, SW Poland. This site represents one of the best developed regional examples of hummocky forest floor relief due to widespread tree uprooting and subsequent degradation of root plates. Through map analysis and dendrochronology the disturbance history was traced to at least the 1930s and, most likely, a strong wind episode from 1933 was the reason for the forest calamity that resulted in the nearly total destruction of the original stand. However, the affected forest was a planted Norway spruce monoculture, introduced and managed until at least the beginning of the 20th century, and not a natural forest. The windthrow niche was then used by beech, whose individuals preferentially chose mounds to grow, conserving the hummocky microtopography. Changes in soil evolutionary pathways brought about by wind-driven disturbance include both haploidisation (rejuvenation) and horizonation (differentiation). Evidence of soil rejuvenation includes a decrease in organic carbon content and an increase in pH in the upper parts of soils developed on mounds relative to the pH of undisturbed references soils. Soil texture was relatively homogenised in pits and mounds. Dating of the pit-and-mound microrelief by means of soil properties (organic carbon content, iron forms) was only partly successful. Although the young age of pits and mounds is evident, the actual age inferred from soil properties was underestimated by a few tens of years. Evaluation of factors potentially controlling the propensity to widespread treethrow suggests that the type of forest is a far more important variable than local abiotic factors of bedrock geology, regolith characteristics, and slope inclination.