Not your everyday nice looking, cone-shaped dome, Obsidian Dome is just another one of the hundreds of volcanic domes as a part of Mono-Inyo Craters of east-central California. At first look, this dome may seem so unattractive that you may not want to waste your time to explore further. But, on the other hand, maybe there are a number of reasons you would want to visit and explore this well-hidden dome.
This dome is primarily made of obsidian rocks. The sharpest natural material known to man, obsidian rocks have played a significant role in the evolution of homo-sapiens' tool-making ability. During the Stone-Age and beyond, in fact far beyond to nearly the present day, obsidian rocks have played a major part as primary cutting tools in many cultures.
The native Americans of this area made tools with obsidian rocks and traded them with other tribes for hundreds of years before the white man stepped onto this land. It is reasonable to assume that hand-collecting obsidian rocks by Native Americans could not have had a significant impact on changing the landscape. Walking the short distance to the top of this dome will demonstrate the impact that heavy mining activity using modern machinery can leave behind.
The summit plateau of Obsidian Dome is wide and convoluted. There are many heavily fractured, unstable rock formations one of which may very well be the highest point. I climbed a few of the high points without knowing whether or not there were other higher points. Hence, no actual summit was reached.
From a mere geologic point of view, however, Obsidian Dome is a very interesting place to visit. According to the informal information brochure provided by the Inyo National Forest, "to understand how obsidian is extruded from the earth, imagine holding a tube of toothpaste upright and slowly squeezing the tube. The thick viscous material forms a column that will fall quickly for lack of solid support. Now go a step further and imagine that instead of toothpaste, your tube is full of melted glass (like obsidian). When the column of glass comes in contact with air, the outside cools and stops moving. The inside of the column continues to move because it's under pressure. The outside skin becomes brittle and falls away." This is the process that occurs here except that the columns are volcanic obsidian oozing from the earth.
Viewed from the parking area, the sides of Obsidian Dome are steep and covered with sharp, angular and black obsidian boulders. You will not readily find lots and lots of pocket-size obsidian rocks due to the fact that the area has been picked over for centuries. The trail to the top area heads north skirting the base of the dome to a secondary parking area and a locked gate. Past the gate, an old mining road rises gently toward the top. A short hike up this road will bring you to a large open area.
This area was constructed as a loading zone for mining trucks. It is obvious that this and all other roads and flat areas were carved out of the top of Obsidian Dome. There are a number of roads leading to dead-end hillsides. Upon further exploration, you will see areas that escaped the ravages of mining activity. The terrain is extremely rough and unstable. It is a good idea to wear gloves and ankle-high boots to navigate the convoluted landscape that was an active volcano in the not too distant past.
To get to Obsidian Dome, drive 10.4 miles north on Highway 395 from its intersection with Devil's Postpile/ Mammoth Lakes Exit to a dirt road called by at least two names, Glass Flow Road and Obsidian Dome Road. Drive about one mile to a fork on the road with a sign directing you to Obsidian Dome.
Another .3 miles up this road to a large parking area. You may drive another .3 miles to a secondary parking area with a gate. Driving to this secondary parking possibility is not recommended for low clearance vehicles.