This cache is placed along Lake Te Anau on a public path. You can take your geodogs to the different waypoints, walk to the stages or ride your bike past the waypoints. This is our third placement and first EarthCache. Well done to Dorset Smugglers on their FTF!
A special thanks to Daywalk for his help with the cache notes and information.
Lake Te Anau is in the southwestern corner of the South Island in New Zealand. The lake covers an area of 344 km², making it the second-largest lake by surface area in New Zealand (after Lake Taupo), and the largest in the South Island. It is the largest lake in Australasia by fresh water volume. The main body of the lake runs north-south, and is 65 km in length. Three large fiords form arms to the lake on its western flank: North Fiord, Middle Fiord and South Fiord. A fiord is a long, narrow inlet with steep sides or cliffs, created by glacial erosion. These are the only inland fiords that New Zealand has, the other 14 are out on the coast. Several small islands lie in the entrance to Middle Fiord, which forks partway along its length into northwest and southwest arms. The surface of the lake is at an altitude of 210 m. It has a maximum depth of 417 m, so much of its bed lies below sea level, with the deepest part of the lake being 226 metres below sea level.
Several rivers feed the lake, of which the most important is the Eglinton River, which joins the lake from the east, opposite the entrance to North Fiord. The outflow is the Waiau River, which flows south for several kilometres into Lake Manapouri. The town of Te Anau lies at the south-eastern corner of the lake, close to the outflow.
The Fiordlands were formed by intense heat and pressure deep in the earth's crust about 500 million years ago, causing the formation of gneiss, schist and granite rocks. These rocks have been thrust upwards by folding of the crust, fragmented by faulting, and at times mixed with molten volcanic rock. Periods of submersion under the sea-bed have created areas of sandstone, mudstone, limestone and granodiorite. The Lake was formed by a retreating glacier in between the Pliocene and Pleistocene eras (between 2 and 10 million years ago) that carved huge U shaped and V shaped valleys in the rock of the flatter fiordlands and melted. The water sat in the carved rock, forming the lake we now know as Lake Te Anau.
Most of these glaciations happened during the ice ages. The Ice Ages spanned from around 2.5 million years ago to 10 thousand years ago. In New Zealand there have been as many as 20 glacial advances, with nine South Island glaciations in the last 700,000 years. The most recent glacial period was the Ōtira Glaciation, between 75,000 and 14,000 years ago.
Sources: 1, 2 and 3
Questions to answer:
Stage 1:
Question 1: Describe the colour and stillness of the lake. Why do you think the lake is this colour?
Stage 2:
Question 2: You will notice a small circular granodiorite (granite) rock on the road side of the path, covered in lichens and mosses. This is one of the types of rock that form part of the Fiordlands and the ground of and around Lake Te Anau. Estimate the rock's height and diameter.
Question 3: How many million years ago where the Fiordlands formed? (Read cache notes)
Optionally, include a photo of the lake with or without your GPS in the photo. Remember to send me an email with your answers within 3 days of logging your visit. Here is a link to my profile:
SaintCache
I hope you enjoyed this EarthCache, and learnt something interesting and new. Happy Caching!