Welcome to Mount Monmot, also known as Monmot Hill.
Mount Monmot is part of the ‘Newer Volcanic Province’ of Western Victoria, and is of regional significance. It is the most recent volcano in the area, having erupted between 50,000 and 100,000 years ago.
It is also unusual because it is a double scoria cone with two craters (also called a Composite Volcano), and displays some distinct volcanic features.
Before looking further at Mount Monmot, here are some volcano basics:
- MAGMA is hot fluid that sits under or within the earth’s crust, and consists of molten and semi-molten rock (eg basalt), crystals, ash and various gases.
- LAVA is the name given to the magma when it reaches the earth’s surface.
- SCORIA is a lightweight basaltic rock that contains small vesicles (holes or cavities). These vesicles are formed when gases that were previously dissolved in the hot magma form bubbles as the magma is forced to the earth’s surface during a volcanic eruption. If the magma is cooled rapidly, these gas bubbles remain trapped in the hardening basalt rock. The basalt rock is usually grey to black in colour, but will weather to a red-brown colour if there is a high concentration of iron rich materials in the rock.
- A SCORIA CONE is formed when hot magma from the underneath the earth’s crust is under extreme pressure and eventually bursts through a vent in the crust as a forceful volcanic eruption. The lava (including the scoria rock) is expelled high into the air and falls around the crater, forming a steep cone.
- SPATTER is formed when the ejected molten lava lumps are still so hot when they land, they stick together as a welded mass of rocks.
- A SPATTER RAMPART is a broad embankment or wall of spatter that is formed on the edge of a crater or a fissure.
- A LAVA DOME (also called a Lava Tholoid) is a dome shaped mound of hardened lava that is formed when some lava has escaped from a vent but has not had enough pressure behind it to expel it into the air or push it out as a lava flow, and thus forms a sticky dome shaped plug instead. Lava domes can be found on lava flows and on the floors of volcanic craters.
Now to Mount Monmot and the Earthcache Logging Requirements:
This is a simple Earthcache with two waypoints, where the features of interest can be viewed from the car.
In order to log this earthcache as a find, you need to answer the following questions and email or message them to the cache owner (chooknchunk).
You may go ahead and log this cache immediately however you need to submit your answers within a week of logging. Logs that are not backed up by submitted answers will be deleted.
Waypoint 1 (Posted co-ordinates).
Make sure you park at the posted co-ordinates as this gives you a safe place to park off the main road. From here, look east across the road to see the Western Crater of Mount Monmot.
- Question 1. Note the rocky outcrop you can see on the rim of the southern side of the crater. From the above volcano basics, what sort of feature do you think this is, and why?
Waypoint 2 (S37 37.829 E143 21.854)
Drive around to Waypoint 2 on the Mount Emu Settlement Road. On your way there you will see a scoria quarry on the side of Mount Monmot - this is not the second crater!!. Find a safe place to turn the car around so you can see the Eastern Crater easily. (If you continue driving up the road a bit before turning around, you will get lovely views of the crater as you approach the waypoint.)
- Question 2. Note the mound of rocks from inside the crater that is just visible behind the rim. From the above volcano basics, what sort of feature do you think this is, and why?
Alternative location to view Waypoint 2 (S37 40.212 E143 21.324)
This is an alternative view of the Eastern Crater, where you are looking for the mound of rocks in the centre of the crater.
And finally...
- Question 3. How do you imagine this volcano erupted? Both craters at the same time? One before the other? (Hint, there is no right answer, this is purely to get you imagining what the eruption might have been like).
Thank you for visiting Mount Monmot.