Basalt fan structure

A basalt fan structure is a basalt formation composed of columnar jointed basalt columns that have slumped into a fan shape.[1]

Columnar basalt Sudurarhraun

They are most likely created when basalt lava is intruded into a soft material, such as loose volcanic ash, which is unable to support the intrusion. As the basalt cools and forms columns, the ash collapses, causing the lava spread and form a fan shape. The formations can be vertical or any degree of horizontal.

References

Faust, George T. "Joint Systems in the Watchung Basalt Flows, New Jersey" (PDF). Geological Survey Professional Paper 864-B. United States Government Printing Office. Retrieved 17 December 2019.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[1] Faust, George T. "Joint Systems in the Watchung Basalt Flows, New Jersey" (PDF). Geological Survey Professional Paper 864-B. United States Government Printing Office. Retrieved 17 December 2019.