Those concentric circles in the rock are really beautiful. Any idea how they formed?
Vic, geologists call that 'flow banding'. Very common in extrusive igneous rocks such as ash flows. Think of the swirls in a marble cake batter. The ash comes out as a dense ground hugging cloud of gas, half melted glass fragments and chunks of all kinds of rock and debris. Look up Nuee Ardant. When the mix of gas and ash cools enough to turn into a hot gloppy mass, that is when the flow banding forms. Later, when long cooled, erosion carves down into the rock, like you would slice a marble cake, and voila -- you have fascinating color bands.
Tony
Edited by AWG_Pics, 12 January 2023 - 02:24 AM.