Basaltbut

Basaltbut is an informal geological term used to describe a basaltic rock outcrop with a buttress-like silhouette, typically standing as a tall, isolated feature within a lava field. The word combines basalt with butt, echoing the shape rather than implying a formal stratigraphic unit. Because it is not part of formal nomenclature, its use is mainly descriptive in field notes and regional surveys.

Morphology and characteristics

A basaltbut usually shows high relief with steep to near-vertical flanks and a relatively flat or gently inclined summit. Surfaces may display visible columnar jointing, especially on exposed faces, and the rock color is commonly deep brown to black. Individual examples can range from several tens of meters to a few hundred meters in height, and they often stand out because of their contrast with surrounding, more weathered terrain.

Formation and environments

Basaltbuts form in basaltic volcanic settings where a resistant basalt block or cap remains after extensive erosion of surrounding rock. They can arise from cooling and solidification features within a lava flow, or from intrusive or extrusive processes that leave a persistent basalt protrusion. Erosion, differential weathering, and the removal of softer surrounding rocks help create the distinctive buttress-like profile.

Relation to other features

Basaltbuts are related to other wind- and water-eroded landforms such as buttes and prominent basalt outcrops, but their defining characteristic is their basaltic composition combined with a pronounced buttress-like shape.

See also

Butte, Basalt, Columnar jointing, Erosion in volcanic landscapes.