Diatreme

When magma rises up through a crack in Earth's crust and makes contact with a shallow body of groundwater, rapid expansion of heated water vapor and volcanic gases can cause a series of explosions.

A relatively shallow crater (known as a maar) is left, and a rock-filled fracture (the actual diatreme) in the crust.

The term diatreme has been applied more generally to any concave body of broken rock formed by explosive or hydrostatic forces, whether or not it is related to volcanism.

At the surface they may be hard to recognise if shallow and dry or eroded and can be up to 3 kilometres (1.9 mi) wide, but are often much smaller.

Kimberlite magmas can sometimes include chunks of diamond as xenoliths, making them economically significant.

Aerial view of the Moses Rock Dike diatreme in San Juan County, Utah [ 1 ]
An illustration using a mix of common and geological terms of a diatreme. The crater and tuff terms are usually combined into the term maar , and maar is often combined into the term diatreme (see text for definitions) rather than diatreme excluding the maar.