Stream-gouged layers of volcanic ashes. Ngaruhoe in the background. Photo NC.

This thick series of layers has been revealed at the surface and is maintained in a fresh state by the continuous backcutting effect of the stream in this bend along its course.
Hardened layers of ashes as visible here are common in series 10,000 years old or more. The more recent Taupo pumice and local ashes that were deposited above have been eroded away. Thousands of years of volcanic history are recorded here.