We learned while at the Hawaiian Volcano National Park that Mt. Lassen errupted in 1917. A batholith is a collection of plutons. Think of it as if you had a blob of dough. If you used a string to push into the dough, it'd create a very narrow valley. If you pressed a thick marker into the dough, it'd create a wide valley.
Glaciers tend to be much, much wider than rivers.
Volcanoes help form the Sierra ages ago, but there are none currently active. Trinica,Priscilla,Sonny from Oro Grande school. Normally, there aren't earthquakes with epicenters in Yosemite, however, we do feel earthquakes. Some of us felt the earthquake down in southern California the other day. Regina,Diana,Kimberly,Daria at Oro Grande.