Phonolite cone
A phonolith cone is a science-historical term that is still used colloquially. It describes the phonolite rock exposed by weathering inside an extinct volcano . In the geosciences , phonolith cone is no longer used as a technical term.
Phonolite cones formed when magma rose from the earth's interior and solidified into phonolite. Mostly it is rock that solidified in the chimney of a volcano at the end of the extraction activity. The original Kegelberg was over time by the removal of the surrounding softer materials by erosion destroyed, and the upper part of the Phonolithkerns was exposed in this way.
Phonolite cones are particularly common in low mountain ranges , especially in the Bohemian low mountain range and in the Lusatian mountains .
In the geosciences today, the term cone mountain is used, possibly with an addition that refers to the type of rock or a reference to its volcanic origin. The term is usually replaced by a term that more precisely describes the formation or the rock, such as a spring tip , stick or chimney filling. In addition to phonolite, other volcanic rocks also form conical and dome-shaped elevations, such as basalt and porphyry .