One of my favorite stops on the South Island was at Kura Tauhiti near Castle Hill. When we first stopped by the side of the road, we could see huge boulders randomly spread out on the hills in front of us. It was a very interesting sight and our curiosity got the best of us as we wondered what they were and how they got there. As we walked up to the boulders, it was amazing to look up at their incredible height compared to the rest of the landscape, which were just grassy hills. I know I certainly felt small in their presence.
Upon closer inspection, we discovered these boulders were outcrops of sedimentary rock, due to the layering of the rock. We also determined the outcrops to be limestone because limestone is a soft rock, which weathers easily and into rounded masses. I could tell just how soft the rock was because people had carved their initials onto the sides of some of the rocks, as if they were wood. These boulders were mostly rounded remnants of weathering of the layers of sedimentary rock. Limestone can erode from natural acids and can be broken by joints where water dissolves or corrodes particles away. We also learned that these towers of rock were called tors, which form from increasing rates of physical and chemical weathering. The weathering gives the tors a scalloped look or honeycomb texture, which can be seen up close. We decided these outcrops must have been formed during the most recent mountain building period because if it had happened before the last ice age, glaciers would have destroyed the tors.
We had a chance to eat lunch there and explore the area on our own afterwards. This site was one of my favorites because not only was it interesting to look at and learn about, but it was also a lot of fun to climb up onto the rocks!
Upon closer inspection, we discovered these boulders were outcrops of sedimentary rock, due to the layering of the rock. We also determined the outcrops to be limestone because limestone is a soft rock, which weathers easily and into rounded masses. I could tell just how soft the rock was because people had carved their initials onto the sides of some of the rocks, as if they were wood. These boulders were mostly rounded remnants of weathering of the layers of sedimentary rock. Limestone can erode from natural acids and can be broken by joints where water dissolves or corrodes particles away. We also learned that these towers of rock were called tors, which form from increasing rates of physical and chemical weathering. The weathering gives the tors a scalloped look or honeycomb texture, which can be seen up close. We decided these outcrops must have been formed during the most recent mountain building period because if it had happened before the last ice age, glaciers would have destroyed the tors.
We had a chance to eat lunch there and explore the area on our own afterwards. This site was one of my favorites because not only was it interesting to look at and learn about, but it was also a lot of fun to climb up onto the rocks!
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