Located in Wheeler Creek, near the east entrance of the park, are
slender spires of pumice. Some of the needles are 200 feet in height. In
Sand Creek Canyon and Godfrey’s Glen in Annie Creek Canyon there are
additional spires and fluted columns carved out of the soft volcanic
material by the erosion of water. As erosion continues the Pinnacles
grow in height and new ones are slowly being formed.
During the summer of 1935, ranger naturalists discovered many small
fumaroles near the top of the gray tuff and ash deposits of Wheeler
Creek Canyon. Some of them are within the pinnacles themselves, regarded
as proof that the deposits were once hot and of the nature of sand flows
like those in the Valley of Ten Thousand Smokes in Alaska.