The Great Reversal
Around half a million years ago, the Kyeburn flowed south through what is now the upper Taiari into the Clutha river system. The rising of the Lammermoor range cut off the river and reversed it. The newly-formed Taiari cut a gorge through basement schist rock at Hyde.
From Mars to the Māniatoto
The Upper Taiari/Taieri River is a very special place. It is one of the only meandering scroll plains found in the southern hemisphere, and the only one of its kind in New Zealand.
Rivers meander on low relief land, where they are free to wander at will across their floodplains, depositing precious, fertile sediment wherever they go. The spectacular hooks and bends that make up a scroll plain are formed as the river abandons an old course and adopts a new one, leaving an "oxbow lake" where it once flowed.
Streamside vegetation is thought to be very important in the formation of meanders — the plants hold the riverside soils together and consolidate the stream banks, allowing meanders to form. If there are few plants, a river is more likely to become braided.
Satellite images now reveal that meandering rivers once flowed on Mars – etched into the barren rock of the Red Planet are the unmistakable coils and bend of old scroll plains. This presents a mystery, because as far as we know plants never grew on Mars, so what held together the banks of these Martian rivers? It may be that minerals dissolved in the Martian soil consolidated it, much like cement.
Famous examples of meandering rivers here on Earth include the Mississippi and the Nile. In both cases, the movement of sediment has created rich farmland that has sustained human civilization and built modern economies. The Upper Taiari is no different the fertile soil it distributes across the Māniatoto forms the basis of the region’s thriving agricultural industry.