Un altro americano del Colorado sul colore rossastro della roccia:

Quote:
In the Grand Canyon, there is a formation called the Redwall Limestone, because it forms <drum roll> red walls. However, the material is not red itself. The color comes from iron oxide leached from the overlying rocks, which are likely siliclastic.http://www.bobspixels.com/kaibab.org/geology/gc_layer.htm#rl

"Data speak for themselves" -Reverend Thomas Bayes 1702-1761
P(Ai|E)=(P(E|Ai)P(Ai))/P(E)