Last November I visited New Zealand to kayak some of the world-class whitewater rivers on the South Island. Of course the beauty of the place is unbelievable. In the making of the Lord of the Rings it seems that no computer enhancing was required. Each day I was there I noticed more and more the differences between the North American continent that I’m familiar with and the island of New Zealand.
Evidence of recent rockslides exist all over the island. Roads that cut across the Alps from one side of the island to the other have concrete covers. These tunnels like covers keep the slides from damaging the roads and travelers. The tops are actually covered from slides that have turned the rockslide covers into the definition of a tunnel. While hiking and kayaking the river valleys, it was easy to spot slides that have occurred recently and had an impact on the river. Many of the New Zealanders treated rocky slopes along the rivers like avalanche territory. They were constantly warning me to be careful when portaging a rapid along the river banks because a rock slide could occur.
The mountains look more like the Rocky Mountains in Colorado except they are more jagged and sharp looking. River gorges form vertical walls on both sides of the river that leave the paddler with no option except running the next rapid with out a clue of what may be around the corner. The rivers are full of sieves and undercut rocks. Rivers of the Southeast America lack the quantity of these dangerous rock features, and they are less dangerous. It seems like our rivers have had more time to erode away or push out the sieves. Sieves are rock placements in a river that let water go through but not a paddler. They are kind of like a colander.
After some research, I found out that New Zealand is basically a plate tectonic mess. The island is actually part of an ancient continent that has sunken, leaving the upper parts of the continent exposed to form the North and South Islands. To the east of the North island and cutting across the South Island is a convergence boundary between the Pacific and Australian plates, which is crunching up to form the Alps on the South Island and other mountain ranges on the North Island. The two plates are converging at an angle, which forms a fault line similar to the one in California. The fault line also splits the South Island. This fault line causes the earthquakes that can cause rockslides. New Zealand is also a geologic infant. The oldest rocks on the island are around 500 million years old. This helps explain why the rivers have not had time to erode away many of the dangerous sieves. However, this is one of the reasons the rivers are so steep and give the country it’s sought after world class kayaking rivers.