Mud Volcano - Part II

Right next to Sour Lake you'll find the Black Dragon's Caldron.  It used to be much more impressive than its current aspect if reports are to be believed.  A sign explains that the feature is over fifty years old for:

This mudpot roared into existence in 1948, blowing trees out by roots and forever changing this once quiet forested hillside.  A park interpreter named the new feature for its resemblance to a darkly colored "demon of the backwoods."  For several decades, it erupted in explosive 10-20 foot bursts of black mud.  Over the years, it has moved 200' to the southeast and become relatively quiet.  However as change is constant in Yellowstone, the black dragon may one day roar back to life. 

--from area signage

This is the current appearance of the caldron:

Now it was quite bubbly as you can see here.

Not all features were this wet however, well you can read the name of the next one, can't you?

It is Grizzly Fumarole and consists of a largely dry feature part of the year.  At times it is merely a steam vent (fumarole) while at other times it can be a large mudpot or series of small mudpots.

When we saw it there was a decent amount of water visible.


But what is a mudpot exactly?  Well I'm glad you asked, ;).

Makings of a Mudpot
The fascinating and mysterious mud features found here are some of the most acidic in the park.  This acidity plays a part in making them different from most hot springs and geysers.  Hydrogen sulfide gas is present deep in the earth at Mud Volcano.  Some microorganisms use this gas as an energy source.  They help convert the gas to sulfuric acid, which breaks down rock to wet clay mud.  Hydrogen sulfide, steam, carbon dioxide, and other gases explode through the layers of mud in dramatic or delightful ways. 

In contrast, the more alkaline waters in most of Yellowstone's geyser basins react with underground rock to line subsurface cracks with silica, creating the natural "plumbing" systems of geysers and hot springs.
--from NPS pamphlet, Mud Volcano Trail Guide

Though Mud Volcano give the area its name, I don't think it looks much like a volcano.  The guide suggests that it likely blew up at some point in the past.

The boardwalk beyond the volcano curved around in front of the next feature that was clearly the most impressive in the area.

Part of the boardwalk had obviously been rebuilt sometime in the recent past as it hadn't had time to fully weather.

There was also a portion that had been torn out.  Change appears to be constant in the park--but the high volume of traffic and harsh weather conditions explain much of this.

The view of the feature was especially impressive from a distance as you could see steam rising, just as it might from the mouth of a dragon.  Thank goodness the National Park Service doesn't engage in corporate sponsorship of features--or to drum up publicity I could see someone trying to name this Smaug's Mouth Spring before the Hobbit movies are released.

And close-up it is even more impressive.

Apparently its previous names have included "Gothic Grotto, Blowing Cavern, and The Belcher."  I think I like the current name the best.  It really does remind me of a dragon lurking in a cave.

Across the parking lot and down the road a short ways you'll find the last feature of the area, Sulphur Caldron.  It isn't easily accessible, but is quite visible from the path.

The pictures from above, and more that couldn't fit in these two posts are located in the following album.


~Matt