Rising like a mirage out the barren desert, this fort shaped National Natural Landmark makes a great side trip when traveling through the Oregon Outback.
Located 70 miles southeast of Bend, Fort Rock can be reached by car in less than 4 1/2 hours from Portland, Oregon.
The enormous monument made of tuff (a porous rock formed by consolidation of volcanic ash) is approximately 4,460 feet in diameter and rises over 200 feet above the surrounding plain.
Designated as a day use only area, Fort Rock State Natural Area (formerly Fort Rock State Park) includes restroom facilities and numerous trails for walking and hiking.
You’ll also find a volunteer park host who is more than happy to answer any questions you may have about this unusual formation rising out of the desert.
Don’t forget to take care of your business before hitting the trails.
The name of the landmark was derived from the tall, straight rock that resembles the palisades of a fort. It was created when basalt magma rose to the surface and encountered the wet muds of the prehistoric lake bottom that was once found here. Powered by a jet of steam, molten basalt was blown into the air, creating a fountain of hot lava particles and frothy ash. The pieces and blobs of hot lava and ash rained down around the vent and formed a saucer-shaped ring of lapilli tuff and volcanic ash sitting like an island in the lake waters. Steam explosions also loosened angular chunks of black and red lava rock comprising the valley floor.
These blocky inclusions are incorporated into the fine-grained tuff layers at Fort Rock. Waves from the lake waters eroded the outside of the ring, cutting the steep cliffs into terraces that rise above the floor of the valley below.
Previous age estimates of Fort Rock ranged upwards to 1.8 million years. Recently, the age has been estimated at 50,000 to 100,000 years. This coincides with a period of time when large pluvial lakes filled the valleys of central Oregon and much of the Great Basin of the western United States. At its maximum, the water in Fort Rock Lake was estimated to cover nearly 900 square miles and was about 150 feet deep where the Fort Rock tuff ring formed.
“A generation after his death in 1974, Reuban A. “Reub” Long still figures in Oregon lore as the “Sage of Fort Rock,” the pre-eminent storyteller and chronicler of the High Desert country. In 1938, a University of Oregon team excavated Fort Rock Cave, on Long’s property, and discovered artifacts that were dated at more than 9,000 years old. Further excavation revealed evidence of human presence at the cave as far back as 11,000 to 13,000 years ago. Reub donated his portion of Fort Rock, including the Cave, for the creation of Fort Rock State Natural Area.” – The Oregon Encyclopedia
It was designated a National Natural Landmark in 1976, a program administered by the National Park Service.
A view from one of the trails that overlooks the parking lot.
There are several hiking and walking trails into and around the extinct volcano…
…but we only had enough time to explore a portion of its interior.
Southerly winds, which are still predominant in this region, apparently drove waves against the south side of the ring, eroding the soft ash layers, breaching it, and creating a large opening on the south side, which can be seen here.
Today, the dry lakebed provides fertile ground for the large agricultural fields that now surround the Fort.
Circular fields which are characteristic of center pivot irrigation, dot the area around Fort Rock National Natural Landmark.
The region around Fort Rock contains about 40 smaller tuff rings and maars (broad, low-relief volcanic craters that are formed when groundwater comes into contact with hot lava or magma). Imagining the valley below filled with water and the rings rising out of it as islands, is kind of mind blowing.
The Shark Fin – The weathered cracks and caves on the steep walls are occupied all summer by prairie falcons & American kestrels, who dine on the abundant small reptiles and mammals that surround the area.
Fort Rock and the surrounding area is not what most people imagine when they think of Oregon. The greener, lusher sections of the state are quite beautiful but some of my most favorite places I visited during my 2016 road trip were actually located here, in the state’s high desert outback. If you plan to visit Fort Rock, I highly recommend taking a 70 mile detour south to Summer Lake Hot Springs, a 145-acre retreat featuring geothermal heated cabins, guest houses, a campground, RV hookups and most importantly, natural rock hot springs and an indoor hot mineral pool. It’s a lovely oasis in this rugged section of the state and a great place to relax when traveling through the area.