 The last eruptions formed Shastina's present summit about a hundred years later.But before that, Shastina, along with the then forming Black Butte dacite plug dome complex to the west, created numerous pyroclastic flows that covered , including large parts of what is now Mount Shasta, California and Weed, California.Diller Canyon ( deep and wide) is an avalanche chute that was probably carved into Shastina's western face by these flows.