A. Penck
(1858–1945)A German mineralogist from the University of Berlin, Penck's main interest was in Quaternary glacial land-forms, which he classified according to shape. Some of his work was done in ...
Aalenian
A stage in the European Middle Jurassic (175.6–171.6 Ma, Int. Commission on Stratigraphy, 2004). See also dogger.
abandonment facies association
A facies association formed under conditions of rising sea level, when clastic deposition has ceased and sediment is deposited very slowly.
abiotic
Not living, non-biological, usually describing factors in an ecosystem: atmospheric gases, humidity, salinity, soil mineral particles, water, and so on. An abiotic environment is one without any ...
ablation
The removal of surface snow or ice by sublimation, melting, or evaporation. The term is sometimes extended to include snow removed by the wind (deflation) and also the calving of glaciers.
Abraham Gottlob Werner
(1749–1817)Professor of mineral science at the Mining Academy, Freiberg, who developed a system of mineral classification which he called ‘oryctognosy’, based on the external characteristics of ...
abrasion
The erosive (see erosion) action that occurs when rock particles of varying size are dragged over or hurled against a surface. Some common agents of abrasion are the bed load of streams, rock debris ...
abrasion ramp
A gentle, seaward slope, with a gradient of approximately 1∘, in an intertidal shore platform that is caused by wave abrasion. The removal of material by wave action leaves the base of the cliff ...
