A lahar occurs when a lake in the crater of an active volcano overflows or the mountain erupts. They're a mixture of water, ice and volcanic debris. Lahars are pretty diabolical, because they generally happen when no one's particularly looking for them (being at the tops of mountains an' all). One occurred on Mt Ruapehu in 1953, swept down the mountain and destroyed the main trunk railway bridge at Tangiwai between Waiouru and Ohakune a few minutes before the daily express between Wellington and Auckland crossed it. A lot of people died.

There's now a lahar warning system on Mt Ruapehu. If you're interested, this link will show you what's what!

http://www.learnz.org.nz/2k/tongariro/t_lahars.htm

Scree is common enough here, Jackie. It occurs on the majority of the mountains in the Southern Alps which are mostly made up of greywacke rock. Scree is loose rock and gravel in a continuous slow landslide. Crossing it carelessly is one of the most common causes of injuries to hikers here in NZ. I got caught in a scree slide some years ago which was set off by the guy I was hiking with. It carried me about 20 metres and then "ran out" on a shallower slope below. But there could just as easily have been a bluff below me and then it would have been "good night all!" For some strange reason I wasn't very polite to him in spite of the fact it was just an inadvertent misstep on his part.


The idiot also known as Capfka ...