The shield volcano that made the Warrumbungles was active about 13-17 million years ago. It rose 3,000 feet (1,000 m) above the surrounding country. Most of the volcano has been eroded, exposing the interior plumbing of small plugs and dikes. This photo shows Belougery Spire, a trachyte plug. A plug is the erosional remnant of a pipe that fed a volcano. Photograph by C. Ollier.
The Breadknife is dike, a tabular-shaped fracture that cuts across pre-existing rock and fed magma towards the surface. The Breadknife is near 2,000 feet (600 m) long and made of trachyte. Photograph by C. Ollier.
The volcanic features are part of Warrumbungle National Park. Photograph by C. Ollier.
Sources of Information:
Duggan, M.B., and Knutson, J., 1993, The Warrumbungle volcano, a geological guide to Warrunbungle National Park: Australian Geologic Survey Organization, 51 p.
Duggan, M.B., Knutson, J., and Ewart, A., 1993, IAVCEI Canberra 1993 excursion guide Warrumbungle, Nandewar and tweed volcanic complexes: Australian Geologic Survey Organization Record, 1993/70, 40 p.
Sutherland, L., 1995, The Volcanic Earth: Sydney, University of New South Wales Press, 248 p.
Volcano Images by Regions To VolcanoWorld