Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Royaume-Uni → 1989 → An integrated approach to the study of mechanical rock weathering and its implications for landforms and landscape development in southern Tenerife

Queen’s University Belfast (1989)

An integrated approach to the study of mechanical rock weathering and its implications for landforms and landscape development in southern Tenerife

Jenkins, Keith Andrew

Titre : An integrated approach to the study of mechanical rock weathering and its implications for landforms and landscape development in southern Tenerife

Auteur : Jenkins, Keith Andrew

Université de soutenance : Queen’s University Belfast (United Kingdom)

Grade : Doctor of Philosophy (PhD) 1989

Résumé
Weathering is investigated at three sites along an altitudinal transect in arid south Tenerife : a low-altitude maritime site ; a mid-altitude site associated with an inversion layer ; and a high-altitude site with clear skies but low air temperatures. External controls on weathering (incoming solar radiation, air temperatures, rock surface temperatures, relative humidity, wind speed) were measured in summer and winter. Internal rock controls (albedo, thermal conductivity, thermal diffusivity and specific heat capacity) upon rock response to microclimate were assessed using blocks of standard rock types. Rock samples, some previously primed with salt solutions, were also used in exposure trials (up to 18 months), and results of weathering assessed using scanning electron microscopy. An understanding of rock controls is refined via controlled laboratory experiments examining moisture uptake and loss. At each site weathering landforms were mapped and examined through chemical (X-ray diffraction and total element) and magnetic susceptibility analyses of fresh rock, weathered rock and weathered debris. Results are integrated to show an overlap of salt and frost weathering mechanisms which produce a range of products and landforms. Rock fragments, scaling and cavernous forms arise from salt weathering mechanisms. Frost shattering is limited to high altitude and produces block shattering and block collapse in igenous rocks. Both mechanisms are significant to change the nature of the landscape. Frost weathering below the surface of debris covered slopes is responsible for altering the nature of the ’basal surface’ through weathering and, at high altitudes, is believed to be the main control on the lateral retreat of upstanding, well jointed igneous material. At mid-altitude sites all the cavernous weathering is associated with block collapse in more resistant layers. At the coast, salt weathering in caverns is directly responsible for cliff retreat sometimes forming surface depressions.

Proquest Dissertations & Theses

Page publiée le 24 février 2015, mise à jour le 30 mars 2017