An avalanche could be able to destroy a whole town.  The wind created by an avalanche can also be dangerous.  The air in front of the avalanche gets pushed in very high speeds.  An avalanche in Switzerland in the year of 1962 had wind that could split trees in half! 

    An avalanche can last for a long time or it could be a short time until it dies off.  The land changes once an avalanche run over the land.  Avalanches carry a lot of dirt from a place to place, it picks up more dirt as it moves.  In one year a river carries a lot of dirt, one avalanche can move as much dirt.  Avalanches carry other things too.