We left the big cities of Christchurch and Dunedin behind us and headed west across the bottom of the South Island. This took us into the mountains of the Southern Alps and to Queenstown. This is the place where all the bungy jumping started and it is still happening there. Imagine a bungy jump. You are standing on a ledge high over a river. You have a cord tied round your ankles. You jump off the ledge and plunge down toward the river and just before you hit it, the bungy cord pings you back up again before you drop down again, bounce up and then down and then you are left hanging over the river. There are lots of places to do this around Queenstown. The area is very mountainous and also has a large number of lakes. This often happens as lakes are formed either when the land is pushed up to make a mountain or during the ice age by glaciers. Oh I forgot to tell you, after the bungy jump they either help you into a raft in the river or wind you back up to the top. They don't just leave you hanging there as I just did. Sorry. For those of you interested I don't like heights so I didn't even go out and have a look but Ev did. And she jumped; three times altogether.

After Queenstown we went to another place where the mountains have an effect on the land. It is a placed called Franz Josef and just outside the town there is a glacier. A glacier is a large block of ice, and I mean large, which is moving slowly downhill. Glaciers are formed at a high level when the amount of winter snow is bigger than that which is lost during the melting period in the summer. Over several years, as water seeps into this snow and the weight of more snow pushes out the air, the ice that is left turns blueish in colour. Gravity then makes the ice mass flow downhill almost as though it was a thick liquid like treacle and when it reaches the lower levels and warms, it melts and turns into a river or a lake. Many of the lakes around Queenstown are fed from glaciers and as a result are really cold.

There are about 140 glaciers in these mountains. One of the reasons that they are there is because the west winds that come across the Tasman Sea carry a lot of moisture. When they rise to climb over the mountains the air cools rapidly causing heavy rain and snowfall. However, only the Franz Josef and the nearby Fox glacier come down so low that they actually run through a rainforest. Sounds weird doesn't it. A glacier in a rainforest. The reason is because of the shape of the land around here. There is a very wide, high block of land and that feeds large amounts of snow into two very narrow valleys. The snow at the top has to be balanced by a large area of melting lower down. For this to happen the glacier has to drop down to an unusually low altitude and reaches the temperate rain forest below.

That's OK but the glacier is constantly moving. The end of it, where the melting takes places, is called the terminal face. In the last twenty years this terminal face has moved about 1 kilometre down the mountain. A glacier is really a bit like a thick river. Indeed right under the ice, just above the rock of the mountain, there is a covering of water. As you know rivers twist and turn and so do glaciers. But as the ice twists it cracks into deep crevasses, which are often narrow gaps, going deep down. Where a river, which reaches a steep drop, will form a waterfall, a glacier forms an icefall. But these icefalls can break off and topple down. The Franz Josef glacier has been known to move four metres a day, which is pretty quick by glacier standards.

The reason glaciers move, and they can go forwards or backwards, is because of the balance of snow at the top and melting at the bottom. If it is cold and there is more snow and less melting, the glacier will advance. This would happen in an ice age. If there is less snow and more melting, when it becomes hotter, then the glacier will retreat. However glaciers are a bit slow to react to weather changes and in the case of the Franz Josef, it takes about five years for any changes to have an effect. Think about that. You go out on a cold winter day and five years later you put on your coat. By the way the Fox glacier takes six years to react. Glacial rivers are often whitish in colour. This is because the constant rubbing of the debris carried down by the glacier leaves a white powder, called rock flour, and this finds its way into the rivers.

It must be so exciting to live in an area where there is a glacier and it is always changing. We met a school in Franz Josef and hope they are going to work with us. If they do they can send us photos each year showing how things have changed. Experts can tell where glaciers have been by looking at the trees on the sides of the valley. If the trees are old, then the ice has not recently reached that level. Younger trees show where the ice may have been. As you can guess, trees cannot survive under the glacier. Waterfalls can also flow down the side of the valleys and into the river formed by the glacier. Again these rivers change more rapidly than ones formed by just water. A melting of a large part of the glacier can result in a sudden flood and a raging river.