Definitions and images to illustrate geological terms, links to images and website articles


The term chonolith is used to describe intrusive igneous bodies with a nonspecific, irregular shape that does not fit into other categories of plutonic structure (such as dike, sill, or laccolith).

A cactolith is a quasi-horizontal chonolith composed of anastomosing ductoliths, whose distal ends curl like a harpolith, thin out like a sphenolith, or bulge discordantly like an akmolith or ethmolith.

Ductoliths are horizontal plugs of teardrop cross section, or a headed dike.

Harpoliths are large, sickle-shaped intrusions injected into previously deformed strata, intruding horizontally in the direction of maximum orogenic displacement.

A sphenolith us a partly concordant, partly crosscutting injected body of igneous rock, in which country rocks are overturned in some sections.

Akmoliths are intrusive bodies injected along a decollement, which send numerous tongues into the overlying folded rocks.

Ethmoliths are cross-cutting bodies of plutonic rock that narrow downward and are thus funnel-shaped.

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