Geology of upper Waitaki Basin
Plains of the upper Waitaki Basin were formed some ten thousand years ago, following the end of the last glaciation. As glaciers retreated, they left behind beds of gravels and boulders.
Ahuriri River
Rivers spilled out of the Tekapo, Pukaki, Ohau and Ahuriri catchments to deposit more gravels and silts. Together, these combined to form the flat inter-montane (between mountains) basin criss-crossed by meandering river channels that we now call the Mackenzie Basin.
The processes of geological uplift, erosion and alluvial transport continue to maintain our braided river and associated wetlands today. Only Alaska, Canada and the Himalayas have extensive braided river systems similar to New Zealand's.