Mt. St. Helens Performs Fast Rock
Before reading the caption, look at the picture of this football-field size mountain of rock at Astronomy Picture of the Day and guess how old it is. The answer: about five months. The smooth rock slab with its cornice tip has grown as much as a meter a day. The caption contains links to more information about the phenomenon.
Someone should date that rock with radiometric methods and find out how many millions of years old it is. Since there are no fossils in it, it must be Precambrian.