Les gnammas sont de petites dépressions localisées essentiellement sur des surfaces horizontales de roche dénudée. Etude de ces gnammas sur les grès calcaires de la vallée de l'Ebre, leur formation serait due à la météorisation par dissolution. (AGB).
Early formation of gnammas (weathering pits) in a recently glaciated area of Torres del Paine, southern Patagonia (Chile)
The gnammas were located on the granite blocks of a lateral moraine deposited during a Late Holocene neoglacial advance. They were measured for maximum and minimum depth, length, and width in addition to other observations, in the Francés Valley
of Torres del Paine. Based on these measurements, the surface area and the volume of the gnammas were calculated. Finally, the Francés Valley population is compared with an older gnamma population to discuss the significance of the results for gnamma
In this paper the AA. carry out a gnamma morphometric analysis (GMA) by quantifying the morphometry of 85 gnammas from exposed granite in western Minnesota. The study site was last covered by the Laurentide Ice Sheet during the Early Holocene
to late Pleistocene transition. The deglaciation of the region was followed by exhumation by paleofloods, which provides further chronological control for the gnamma population. A special emphasis is placed on the comparison of the depth ratio/age
relationship determined for this site with other well established gnamma localities around the world. Finally the AA. discuss the possible processes that may account for variations in the depth ratio.
Diurnal and seasonal water variations of temperature, pH, redox potential and conductivity in gnammas (weathering pits) : implications for chemical weathering
This study describes the main hydrological processes in gnammas and the underlying chemical interactions with the environment. Four gnammas developed in a granite tor from central Spain were chosen for monitoring and studying the dynamics
of the gnamma-water system. Parameters monitored were air and water temperature, pH, ORP (redox potential), and conductivity. These measurements describe the system dynamics, without the need for special sampling or other potential interferences under low water
Micromodelado granitico : ejemplo de gnammas en un afloramiento del noroeste peninsular
Cristallin ; Espagne ; Galicia ; Gnamma ; Granite ; Géographie de l'Europe ; Micromodelé ; Météorisation ; Pia
Analyse du micromodelé granitique, en particulier les Gnammas , pias en Galice : petites concavités localisées sur des surfaces planes ou légèrement inclinées. Sont classées suivant plusieurs paramètres : types de fond, formes des parois, critères
Les rock doughnuts (littéralement pets de nonnes rocheux) sont les rebords en surplomb de cavités de météorisation (gnammas) creusées dans des roches cristallines. Exemples pris dans les Waddikee Rocks gneissiques, dans le Nord de la Péninsule