Cache of the Month December 2019 – Umpherston Sinkhole

The Limestone Coast is abundant with sinkholes. This one is popular with tourists who visit Mt Gambier. The well maintained gardens are a feature as you walk down the staircase to the bottom of the sinkhole.

Umpherston Sinkhole GC1FZY0 is an earthcache created by Team Rubik and was published on 5th September 2008. It has had 446 logs since that time and received 79 favourite points.

The earthcache asks you to discover and answer relevant questions on how the sinkhole was formed.

“Limestone is composed almost entirely of calcium carbonate (CaCO3), a mineral which dissolves in the presence of acid. Rain and groundwater can become mildly acidic when the water reacts with carbon dioxide in the air and soil. Over thousands of years this acidic water can dissolve substantial volumes of limestone, particularly where fractures in the limestone allow the acidic water to seep into the rock. Large sections of limestone may weaken or dislodge as a result of this, causing large sections to cave in.   Some dramatic changes to the topography around Mount Gambier, such as Umpherston Sinkhole, are an example of this process.”

Although the information sign is missing a little bit of research will help with the answers.

The beautiful gardens have been the venue for weddings and family gatherings.

In the evening you are greeted by the friendly possums hoping for a feed of fruit particularly apples so remember to bring some along with you. It is especially exciting for children to visit the possums.

What cachers have said in their logs:

“This place is AMAZING!!! Aside from the geology (the subject of this Earth Cache), the gardens are stunning and the foresight to plant the way that they have has yielded amazing results. I love it here. If I lived here I would be down here all the time. We passed several people feeding the possums. This is a bit odd to us given that we have one (or a family) living in the roof of our house. Thank you for the Earth Cache Team Rubik – you have chosen a truly spectacular location.”

Log by TeamUs!

“Wow, this place is just amazing! Thanks for bringing us here and for helping us understand how these are formed. FP from us”

Log by Boeing737

“What a fantastic place. We loved learning about the history of the place, both the geological and the preservation history. We really enjoyed our time wandering around the sinkhole, and the broader park. Thanks!”

Log by jaw_fnq

Inline with Geocaching SA’s goal of promoting the past-time of Geocaching is South Australia, each month the association will be highlighting a cache that warrants recognition. There are no specific criteria, and suggestions are welcome, but final discretion lies with Geocaching SA.

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