The Wall of Waiau

At just after midnight on the 14th November 2016 a magnitude 7.8 earthquake ripped through the countryside of north-eastern South Island. While the human impact effects of earthquakes are indeed sobering, earthquakes are also the vibrations caused by movement of the Earth's tectonic plates that cover the surface of this dynamic planet we call home. Without plate tectonics the islands of New Zealand would still be underwater and we would not have the dramatic and beautiful landscape that is renowned around the world. Fault ruptures like in this event have occurred many times in this region and throughout the South Island over the last 25 million years to slowly build up the mountains we see today.
The fault scarp viewed at this location is around 3.5 m in height.

The geology here is Middle Miocene - Pliocene aged (around 2-15 million years old) Greta Formation, a formation usually dominated by fine-grained marine siltstones, where deposits up to 800 m thick can be found near Waiau township, but also contains conglomerates and sands. The Greta Formation deposits record near-shore marine and some coastal on-land environments as the local region was uplifted out of a shallowing ocean by the ongoing tectonic growth of the Southern Alps (due to tectonic plate collision).

It's a rare opportunity to see "fresh" fault ruptures. The effect of pushing up a block of the ground relative to it's surroundings (and depending on it's geologic properties) creates a fault scarp that is more prone to erosion and will get smoothed over fairly quickly. It has always been a challenge for geologists trying to work out how much and how often a fault has ruptured in the past (and therefore how often it might do so again), when much of it may have been eroded away!
This event moved through the landscape at around 1.8 km per second (over 6000 km per hour!). Therefore this relatively tiny scarp formed incredibly rapidly!

Notice how there is now a pond in front of the scarp - why do you think this has developed? This fault rupture also moved sideways as well as vertically. Can you see any evidence of the sideways movement? It's a lot more subtle to pick up than the obvious vertical movement! HINT: see if you can find any offset sheep tracks or bushes.
Erosion is playing a large role in the evolution of the scarp today. Compare what you see in front of you to the original photos taken just after the earthquake in 2016. How has the scarp changed over time? Have a closer look at the Greta Formation geology that is exposed in the scarp. What is the grainsize of this unit? How soft or hard is it? What effects might physical or chemical weathering have on this unit over time? This unit underlies much of the Woodchester Station land - what hazards might be posed to the landowners and range of activities they might use the land for? Consider effects on forestry, stock, infrastructure, services. How might they be able to reduce or manage the effects?