Bumpass Hell has the largest concentration of geothermal features in California’s Lassen Volcanic National Park. A moderate 3 mile round trip hike from the parking lot 6 miles from the south entrance takes you to an active hydrothermal basin to see, hear and smell fumaroles, boiling mudpots and hot springs.
While there are several areas of hydrothermal activity that you can visit in Lassen Volcanic National Park including Sulphur Works, Devils Kitchen, Boiling Springs Lake and Cold Boiling Lake the hottest and most vigorous features are at Bumpass Hell.
The basin, mountain and other features of the area are named after Kendal Vanhook Bumpass, a mountaineer and explorer who is said to have injured himself on his first visit in 1864. Undeterred he and a partner, Major Pierson B. Reading, filed a claim with the intention of mining minerals and developing the area as a tourist attraction.
That plan never materialized, likely because of Bumpass’ second (and only confirmed) accident as described by one of his companions:
“Our guide [Mr. K. V. Bumpass] after cautioning us to be careful where we stepped, that the surface was treacherous, suddenly concluded with Virgil that the “descent to Hell was easy” for stepping upon a slight inequality in the ground he broke through the crust and plunged his leg into the boiling mud beneath, which clinging to his limb burned him severely…”
Editor, Red Bluff Independent, 1865
Bumpass Hell Basin and Trail Pictures
This is our destination, Bumpass Hell Basin. You are likely to hear and, depending on wind direction, smell it before you actually see the basin as you top the ridge and begin your descent. On my visit in mid-August the impression was of distant jet engines.
We begin our adventure where our last visit ended, at the Kohm Yah-mah-nee Visitor Center at the south entrance to the park.
The Kohm Yah-mah-nee Visitor Center is open daily except December 25 and provides several well designed exhibits, park publications; maps, trail and road guides, field guides and children’s activities. Ranger-led programs, gift shop, restaurant, restrooms, first aid and other services are available.
Emerald Lake lies between the south entrance and Bumpass Hell parking lot.
The warm waters of this shallow glacier shaped lake support abundant green algae, rare in a lake at this altitude.
You also pass Sulphur Works, Lassen VNP’s most accessible hydrothermal area, which I covered in my earlier essay.
The drive from the Visitor Center to Bumpass Hell parking lot is through the caldera of an ancient volcano—Mount Tehama, also known as Brokeoff Mountain. The parking lot and trail head are at about 8000ft elevation, just below the roads high point of 8512ft near the Lassen Peak parking lot and trail head.
Having reached the Bumpass Hell parking lot and trail head you may want to take a few minutes to
circle the lot to enjoy the views and read the several informative signs explaining the geography of the area.
The above photo, from the edge of the paved parking area, shows a glacial erratic—a bolder out of context.
A nearby sign explains: …volcanoes are mountain builders, glaciers mountain remodelers. Glaciers carve,
grind and excavate mountains. The smooth rocks at your feet were worn by the friction of a glacier that moved
over it about 18,000 years ago. The lone bolder was plucked from Bumpass Mountain behind you and carried
by gravity as the glacier moved downhill and deposited it here as the glacier melted.
There is more to see from here and several additional informational signs but lets get started on our hike.
The photo below is of a sign showing the route we will be traveling around Bumpass Mountain to Bumpass Hell Basin. As you can see it is also possible to hike to the basin from Kings Creek picnic area and the south entrance Visitor Center.
The Trail to Bumpass Hell
A short walk into our hike we pass Lake Helen.
This is one of the most popular hikes in Lassen VNP and the Bumpass Hell parking lot fills up frequently.
You may find parking at Lake Helen and either walk the short distance back to Bumpass Hell parking lot or take a short cut directly to the trail.
I have a nice shot of Lake Helen with a bit of ice on it and surrounded by snow in my earlier LVNP photo essay.
The trail is narrow but the ascent so gradual that it is easily navigated. Its moderate rating is probably a result of the steeper descent into the basin at the end. You may have to stop frequently to accommodate foot traffic in the other direction.
Along the way you will be able to look back at the parking lot you left from and see several peaks that are remnants of the huge volcanic mountain that once occupied the area you are viewing. Brokeoff Mountain is on the left. Mount Diller near the center and Pilot Pinnacle on the right.
A short side trail leads to nice views including Brokeoff Mountain in the telephoto shot above.
An informative graphic at this location explains how several peaks were part of ancient Brokeoff Volcano (Tehama Mountain).
I didn't get a usable shot of that graphic so am including a similar one from the parking lot below.
The graphic above is a bird’s-eye view from roughly the location of Lassen Peak which is approximately 1,000 feet shorter than Mount Tehama’s original height.
The top photo in this essay shows the first view of Bumpass Hell as you begin your descent into the basin. Bumpass Hell Basin, although much smaller, has much in common with and reminds me of Porcelain Basin at Norris Geyser Basin in Yellowstone NP.
The above panorama is from a low hill near the edge. Bumpass Hell has fumaroles (steam vents), mudpots and hot springs—three of the four main types of geothermal features. All thats missing are geysers which require different conditions than those found in Lassen Volcanic National Park. All of the surface material here is in a constant state of change. The bubbling mud was once solid lava rock. Heat, water, gases and time have altered the rocks to clay.
Although Bumpass Hell is outside the original Brokeoff Mountain Volcano you can see the same processes at work here that,
along with glacial activity, reduced the former giant mountain to its current state. A nearby graphic explains:
The lava rock that once filled this area has been eaten away and altered into clay by sulfuric acid. The acid can be linked to a high temperature form of sulfur (sulfur dioxide) released from the magma body that fires Bumpass Hell. The rotten-egg smell that fills the air can also be linked to sulfur. It is hydrogen sulfide gas, a forerunner to the formation of sulfur—yellow, pyramid-shaped crystals that form on the ground here. The white and orange-yellowish ground crusts are also sulfur relatives, called sulfates. Sulfate-rich water evaporates at the surface, leaving the colorful sulfates behind. The sulfates build up in ground crusts and change colors, depending on how wet or dry the crusts are.
The roaring sound you hear in Bumpass Hell comes from fumaroles like the one above.
A U.S. Geological Survey Fact Sheet explains that water from rain and snow falling on highlands of the park enters the ground through permeable rock and pathways such as fractures, faults and volcanic flow boundaries. Deep underground it is heated by a body of magma or solid but very hot rock and then raises from 5–6 miles below the surface to about one mile to half a mile below where it accumulates at temperatures of 455–464°F (235–240°C). As it rises acids react with surrounding rock enriching in dissolved silica and metals. As the superheated water gets closer to the surface lower hydrostatic pressure causes it to boil eventually reaching the surface through fissures as steaming fumaroles or boiling at the water table creating areas of steaming surface features such as boiling mudpots and pools.
A process called hydrothermal alteration which happens when acidic water chemically changes minerals in rocks
produces a white material rich in kaolinite clay and silica which is abundant at Bumpass Hell.
The steam rising from the fumarole above was hot enough to be uncomfortable if it blew against you as you walked by.
This is the section of the boardwalk leading to Big Boiler.
I had to wait for a breeze to blow steam away to get a shot of Big Boiler fumarole.
Steam from this fumarole can be seen rising behind a hill at the left end of the boardwalk in the very first picture of this essay.
This telephoto shot of Big Boiler fumarole—the largest fumarole in the park—shows discoloration of the rocks from sulphur,
other minerals and possibly some organisms. High velocity steam from Big Boiler has been measured as high as 322°F (161°C) making it the hottest fumarole—within a non-erupting volcano—in the world.
Constant churning action and heat cause the collapse of surrounding clay crust constantly enlarging the fumarole
Big Boiler even engulfed a portion of the boardwalk a few years back.
West Pyrite Pool is directly across the boardwalk from Big Boiler. Water from here runs into East Pyrite Pool.
The stream emptying into East Pyrite Pool only slightly cools the boiling West Pyrite Pool.
The black scum on the surface is tiny pyrite crystals, an iron-sulfide mineral perhaps better known as “Fools Gold.”
Iron leached from the rocks below by rising hot water combines with sulfur to become pyrite at the surface.
Mudpots, like these at Bumpass Hell, are the intermediate phase between a fumarole and a boiling spring.
They have less water than a boiling spring, more than a fumarole and vary from year to year depending on the amount of moisture.
For a close-up photo of a boiling mudpot check out my shots of Sulphur Works in my earlier photo essay on Lassen. The next essay covers a nearby lava tube known as Subway Cave.
Find iNeTours.com on Facebook or follow us on Twitter for updates, Photo-of-the-Day, more.
Website and all photos copyright © 2001–2016 Lee W. Nelson