When magma solidifies at the crest of an anticline or at the bottom of a syncline, the feature formed is called

When magma solidifies at the crest of an anticline or at the bottom of a syncline, the feature formed is called a "laccolith". A laccolith is a type of igneous intrusion that forms when magma is injected into a sedimentary layer and spreads out in a lens-shaped mass between the layers, causing the overlying layers to bulge upward. The magma cools and solidifies underground, forming a dome-shaped feature. Unlike a batholith, which is a large, irregularly-shaped body of intrusive rock that forms deep underground, a laccolith is a smaller, more localized intrusion that is typically lens-shaped. A phacolith is a similar feature, but it forms along the fold axis of a syncline or anticline, rather than at the crest or bottom. A lopolith is a saucer-shaped intrusion that forms when magma is injected into a basin-shaped depression in the rock.