Brodlsulz - die einzige Mofette Österreichs EarthCache

Caution: Please stay on the trail!

To answer the questions, it is not necessary to leave the path - because despite their low temperature, mofettes are not without danger. They emit the gases carbon dioxide and carbon monoxide. The gases are usually odorless and heavier than air. The gas can therefore accumulate in depressions in the ground and reach high concentrations that displace the air we breathe!

What is a mofette?

A mofette is an opening in the ground from which the gas carbon dioxide (CO₂) emerges at a temperature of less than 100 degrees Celsius. In addition to carbon dioxide, mofettes can also emit the gases nitrogen, methane gas, helium, other rare gases and hydrogen sulfide, the latter of which is noticeable due to its smell of rotten eggs. Real mofettes contain at least 98% carbon dioxide. The name "mofette" originally comes from Latin and can be translated as "harmful fumes" or "musty smell". Mofettes are considered a subspecies of fumaroles (these are hot gas springs) and are viewed as post-volcanic phenomena, with fumaroles occurring primarily in volcanically active areas. Mofettes also form in regions that are only magmatically active but otherwise show no above-ground volcanism.

Mofettes can have a varied appearance, ranging from dry gas seeps to mud pots to mineral springs containing carbon dioxide. As a rule, they arise (as in the case here) because organic materials were buried long ago through rock layers (of volcanic origin), which are now in a state of peatification or coalification, whereby gases, primarily carbon dioxide, are released which reach the surface through fissures. Mofettes are often found near plutons, i.e. magma bodies that have risen in the earth's crust and not yet cooled down. In such areas, like here in the volcanic region of Styria, mineral and thermal springs often emerge and are said to have healing properties.

Mofettes pose a certain danger for living beings because the escaping carbon dioxide, which is heavier than air, collects on the ground - especially when the mofette is in a lower location, such as at the bottom of a depression in the terrain. Such a sink filled with carbon dioxide can become a deadly trap - usually for small animals such as insects, amphibians, birds or smaller mammals such as rodents. Sometimes larger animals also fall victim to the carbon dioxide, viewing the animal corpses on the edge of the mofette as food. According to tradition, a person died in the mofette area near Klapping when he wanted to drink from the spring pool and was looking for his lost watch on the ground. In any case, it is advisable not to spend too much time in the immediate vicinity of the mofette.

The so-called "Brodlsulz" near Klapping

The so-called "Brodlsulz" near Klapping/Styria is the only known mofette in Austria - it is not only because of this unique position that it is a phenomenon worth visiting. It lies on the southeastern edge of a former lava flow, where volcanic fissures reach deep into the earth's crust. Here, organic materials were once buried and covered by lava, volcanic ashes and, in the course of several floods throughout earth's history, also by mud. These organic deposits turn into peat and carbonize, and the resulting carbon dioxide comes to the surface in form of a mofette. Depending on the water level, the "Brodlsulz" can form a smaller or larger water basin from which the gases rise bubbling, like "simmering" - hence the name (because German "brodeln" means "to simmer").

To log the Earthcache, you must answer the following questions via message:

1.) What does the mofette look like at the time of your visit - dry, a mud hole or a bubbling pool of water?
2.) How do the gases come out - slowly, in individual gas bubbles or more violently?
3.) Can you smell anything? If yes, describe it!
4.) Look at the stream a few meters away from the mofette - are gas bubbles emerging here too? If so, does it look different to the mofette or is it the same?
5.) Optional: Post a photo of yourself or your GPS near the header coordinates along with your log entry.

Once you have sent your message with the answers, you can log the Earthcache as found. There is no need for log permission! If something doesn't fit, I'll let you know via message. Have fun!

The most exciting way to learn about the Earth and its processes is to get into the outdoors and experience it first-hand. Visiting an Earthcache is a great outdoor activity the whole family can enjoy. An Earthcache is a special place that people can visit to learn about a unique geoscience feature or aspect of our Earth. Earthcaches include a set of educational notes and the details about where to find the location (latitude and longitude). Visitors to Earthcaches can see how our planet has been shaped by geological processes, how we manage the resources and how scientists gather evidence to learn about the Earth. To find out more click HERE.