USGS Geology in the Parks
Green Sand Beach, Hawai'i
This image, and all pictures of the green sand beach were
taken by Rianda and Adam Levin ©
Drive to South Point on the Big Island and get ready for a hike:
sturdy shoes and plenty of water are required. The trail is about
two and a half miles long, and towards the end of it you'll get
your first look at the remnants of a cinder cone - the source of
the green sand. Visible just above the rim is a glimpse of the olivines
being washed down the slope.
The cinder cone is mostly eroded, only a fragment remains. The
rapid erosion rate provides a contsant source of olivines for the
beach sand. High wave energy of the beach washes the other grain
types out to sea, however it also eventually wash away the olivines.
Only the rapid erosion rate of the cinder cone keeps the beach supplied
with its green sand. Eventually the last of the cinder cone will
be completely eroded and the beach will look like any other.