Earthquakes
On October 28, 1983, a major earthquate
fracture, 26 miles long and
7 miles deep, surfaced as Lost River
Valley slid away from Mount Boran.
During that rock shift, Mount Borah's ridge
front rose about 6 inches, while this valley
subsided 9 feet. This kind of movement has
been going on here for 10 to 20 million years
as subsurface rock has been pulled apart during
gradual but persistent range and valley building.
You can drive to a spectacular fracture that
shatter this side road 2-1/2 miles
from here.
