#pillow basalt

Inside the plumbing system of an ancient volcano

A fossil plumbing system of an ancient Waitakere Volcano. Though the volcano went extinct and was largely eroded away, the lava flows that once spew from it are now preserved along the Maori Bay coast. The radial feature is an internal view of lava flow lobe that shows rosette style columnar jointing. This feature forms when large lava flow moves and cools slowly, allowing columns to grow, which at the same time are bent due to ongoing lava movement.

Muriwai, New Zealand

A detailed description of this flow is available in the following article:

Bear, A.N. and Cas, R.A.F., 2007. The complex facies architecture and emplacement sequence of a Miocene submarine mega-pillow lava flow system, Muriwai, North Island, New Zealand. Journal of volcanology and geothermal research, 160(1-2), pp. 1-22.