July 8, 2011

Geology Word of the Week: F is for Fumarole

Posted by Evelyn Mervine

Fumarole 1. Yellowstone, Western USA, Fall 2005.

def. Fumarole:
A crustal opening, usually in the vicinity of a volcano, through which steam and other hot gases– such as carbon dioxide, sulfur dioxide, and hydrogen sulfide– are emitted. Fumarole comes from the Latin word “fumus,” which means smoke. According to the Oxford English Dictionary, the word was incorporated into English through the French word “fumarolle” [1].

When I’m pondering my geology word of the week, I usually start by reading several definitions of the geology word which I have chosen for that particular week. My trusty geology dictionaries rarely fail me, and I also often read the word’s entry (if it exists) on wikipedia (which is sometimes well-written; sometimes not) and check to see if the geology word is in the Oxford English Dictionary or OED. The OED is a great place to trace the etymology (origin and history) of a particular word. Sometimes geology words are in the OED (for instance, the words “delta” and “fumarole”), and sometimes they’re not (for instance, the word “nabka”). The OED definitions are usually elegantly written, but they are not always perfectly scientifically accurate. After reading several definitions– and sometimes sections of geology books related to a particular word– I set everything aside and then write up my own definition. I then add a little explanation and some pictures, edit a little, and then my geology word of the week is complete!

I really try to write the geology definitions in my own words and not just copy them out of books or online sources. However, this week I find myself particularly enchanted by the OED definition of “fumarole,” which is:

A hole or vent through which vapour issues from a volcano; a smoke-hole [1].

While perhaps not the most scientifically accurate and complete definition, I think that “smoke-hole” is a great way to describe a fumarole. Perhaps “gas-hole” would actually be better since a fumarole does not really release smoke from a fire but rather gases, generally hot gases generated by nearby volcanic activity. However, fumaroles do sort of look as if they are releasing fire smoke. Fumaroles often occur together in a “fumarole fields.” From a distance, a fumarole field can make a landscape look as if it is on fire, or perhaps smoldering after a recent fire. Indeed, one of the largest and most famous fumarole fields occurred in Alaska in 1912 and became known as “The Valley of Ten Thousand Smokes.” This impressive field of thousands of fumaroles formed in gas-rich volcanic ash that covered the valley after a very large eruption of the Novarupta Volcano.
However, fumaroles do not erupt smoke, at least not proper smoke generated by the burning of something. Rather, fumaroles release hot gases such as steam (water vapor), carbon dioxide, sulfur dioxide, and hydrogen sulfide. A fumarole which releases primarily sulfur-rich gases actually has a special name: it is called a solfatara (plural: solfatare). The gases released by fumaroles are generally produced as a result of volcanic activity and are generally being released from hot, gas-rich magma or ash. Water vapor released by fumaroles could also be the result of volcanic heating of groundwater.
Below are fumarole pictures galore! Enjoy!
Here are some pictures of fumaroles that I took during a trip to Yellowstone back in 2005:
Fumarole 2. Yellowstone, Western USA, Fall 2005.

Fumarole 3. Yellowstone, Western USA, Fall 2005.

Fumarole 4. Yellowstone, Western USA, Fall 2005.

Fumarole 5. Yellowstone, Western USA, Fall 2005.

Fumarole 6. Yellowstone, Western USA, Fall 2005.

Fumarole 7. Yellowstone, Western USA, Fall 2005.

Here are some fumarole pictures and descriptions sent to me by Erik Klemetti of Eruptions:

Fumarole field at Bumpass Hell near Lassen Peak, California.
Photo courtesy of Erik Klemetti.

 

A fumarole near the road at the southern entrance of Lassen Volcanic National Park.
Photo courtesy of Erik Klemetti.

These aren’t active fumaroles, but the pinnacles in the Crater Lake ~7700 year old
eruption deposits are fossil fumaroles formed as the tephra degassed.
The ones in this shot are along the southern entrance road to the National Park.
Photo Courtesy of Erik Klemetti.
A fumarole in a sewer grate in downtown Rotorua, New Zealand.
Photo courtesy of Erik Klemetti.

Fumarole in front of some colonial buildings along the shore of
Lake Rotorua, New Zealand. Photo courtesy of Erik Klemetti.

Here are a few more fumarole pictures from Yellowstone sent to me by Chris Rowan of Highly Allochthonous:

Beryl Spring Fumarole, Yellowstone, Western USA. Photo courtesy of Chris Rowan.

Black Growler fumarole. Yellowstone, Western USA. Photo courtesy of Chris Rowan.

Grizzly fumarole. Yellowstone, Western USA. Photo courtesy of Chris Rowan.

Reference:
1. “fumarole, n.” The Oxford English Dictionary. 2nd ed. 1989. OED Online. Oxford University Press. 7 July 2011  .

***Thanks very much to Erik Klemetti and Chris Rowan for pictures of this week’s geology word.***