The characteristics and morphology of columnar dacite in Tawau, Sabah

Abstract

The occurrence of columnar jointing is commonly associated with volcanic rocks and a rapid cooling environment. We recently discovered well-preserved columnar dacite on the road cutting slope in the eastern part of Tawau town, Sabah. This paper briefly describes the occurrences and morphology of columnar dacite in the study area. Columnar dacite exhibits entablature feature since it has thinner and chaotic columns. The hexagon side dominates the columnar joints with minor pentagons to heptagon sides. Columns for dacite are much smaller compared with columnar basalt Tawau. The formation of columnar joints was influenced mainly by external fluid where the water flow on top of the cooling lavas makes it cool rapidly.