Farther down U.S. 20, you ease into the Great Basin desert and such attractions as the Sagehen Nature Trail, located 70 miles from the Pine Mountain Observatory [1] turnoff, and the Glass Buttes.
Located 36 miles past the observatory, the Glass Buttes are one of the world’s largest obsidian outcroppings, a mountain of volcanic glass gently rising 2,000 feet above the surrounding countryside.
The Bureau of Land Management (541/416-6700, www.blm.gov [2]) can provide you with additional information. From here the next big town is Burns, 55 miles to the east.
Links:
[1] http://www.moon.com/destinations/oregon/central-oregon/bend/sights/pine-mountain-observatory
[2] http://www.blm.gov