Prabighya - Geo Postcard

Braided Streams:
Braided stream was one of the most interesting features of a river system that I have learnt about during the trip. A braided stream is one where a channel divides into many small networks within the stream itself, in a pattern which to me appeared very much like its name suggests; braided. The characteristic feature of the braided river that we saw in Waimakariri river and Harunui river were that they were both in broad low land valleys adjacent to the mountain ranges. Although it is a river but the volume of water is very less and so the sediments are well exposed. This exposed sediment of the river bed is highly subjected to the effect of drying out due to the lack of enough water. This dry sediment provides an ample opportunity for the sediments to be easily affected by the wind action where the wind carries the dried out fine sediments and allows for loess deposition to occur in the wind blown direction. Loess is a blanket of un stratified , wind deposited fine grained sediment which is rich in clay minerals.
We also got the chance to see cloud of loess going above the braided river system of Waimakariri river during our drive.

Tower Karst Topography:
During our stop in Kura Tawhiti Conservation area which was about 920m from Castle Hill, we got to see some remarkable work done by nature on limestone which is a kind of sedimentary rock. Limestone is formed from layers of organic sediment deposited in deep oceans far from land. The resulting rocks can end up hundreds of metres above sea level during periods of mountain building. Limestone is composed of calcium and carbon which is soluble in the weak carbonic acids that are present in rain water which works on joints in soft rock, gradually enlarging them. Small differences is present in the rock structure and the solubility which leads to a wide range of pits and grooves and variation in structure that can be observed as each huge boulder is different from the other in terms of shape and structure. These sculptured landforms are the results.