Green Canyon Road, also known as State Highway 167, takes you on a journey along the Henrys Fork Caldera rim shaped by a cataclysmic volcanic eruption approximately 640,000 years ago. As you drive, occasional views extend as far as the snowy Grand Tetons in the distance, offering a glimpse of the transformed landscape amidst the lush forests. Could this have once been a more rugged terrain, with deep river canyons, mud pots, and geysers, before the eruption and the migration of the lava chamber beneath what is now Yellowstone National Park? Along the roadside are outcroppings of ancient basaltic lava flows, leaving boulder-like features scattered throughout the forest. This trail also offers access to other trails, inviting exploration along with hiking, fishing spots, and serene camping areas, providing an opportunity to connect with nature and immerse yourself in the region's rich history. The history of Green Canyon Road can be traced back to the early settlement of the area, where pioneers and explorers relied on trails and rudimentary roads to traverse the wilderness.
An article from USGS describing the 2.1 million years of volcanic history in the area can be found here. This is a great article that explains the volcanic history you'll see as you drive toward Yellowstone National Park from Ashton, Idaho.
There are no obvious campsites along this road, but off the intersecting trail 465 lies West End Campground, located on the edge of Island Park Reservoir. West End Campground is a dispersed camping area with a vault toilet and no other amenities. Day-use activities and rental accommodations are available at Harriman State Park near Highway 20 and Island Park.
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