…where volcanoes rained on giant sequoias
Brochure | Map
Fifty million years ago, this area was much different. The climate here was cool and wet much like the Coast Range. Giant sequoia forests covered rugged, hilly highlands. Ferns blanketed the forest floor. The Salmon River flowed south from here to the Snake River Plain.
Volcanism started in this area 51 million years ago from a variety of vents and continued until about 40 million years ago. Flows and tuffs cover almost 1,900 square miles of east-central and south-central Idaho and are up to 10,000 feet thick.
Twin Peaks caldera, west of Challis, is roughly 12.5 miles in diameter and is the major source for the volcanic ash in Malm Gulch. During its eruption, ash fell from the sky and flowed on to the existing rugged highlands of Precambrian and Paleozoic sedimentary rocks. It engulfed and petrified the sequoias that once grew here.
Panel on site interpreting the volcanic ash falls on the sequoias at Malm Gulch.
Lavender, light green and white hillsides formed after the volcanic ash cooled and solidified. Remnants of this giant sequoia forest can be found by walking 1/2 mile up this trail.
Fences were installed in the 1970s to protect the last examples of an ancient, petrified sequoia forest. These 50 million year old sentinels are all that remain of what was once a large sequoia forest.
Petrified wood has been a coveted material for thousands of years, appearing first in the prehistoric record as stone tool materials, and later in the collections of rock collectors and jewelry makers.
Please enjoy these last remnants, but do not take them. Leave them where they stand so that others can appreciate them.