Hidden away in the southwest of Tasmania is one of the most beautiful places, Lake Rhona. This is a little lake (~ 300 m2) in the mountains surrounded by some neat rocks, in a pretty interesting geological area. It takes a bit of a bushwalking (i.e., hiking) effort to get to, but is well worth it if you predict the weather and choose your days wisely!
Getting there
The hike to Lake Rhona starts well in the temperate rainforest setting of the Florentine Valley. I won’t describe how to do the trek to Rhona in detail (lots of other websites do this already!), but some highlights include:
(1) A substantial crossing of the Gordon River (with a conveniently placed fallen down tree that allows a dry-sock crossing)
(2) A never-ending marsh (that will ensure your dry socks now are wet and muddy)
(3) A breathtaking (literally) ascent up a never-ending moraine
(4) A breathtaking (not-so-literally) glimpse of Lake Rhona at the very end right before you descend to the white-sand beach for camp.
About the landscape and rocks
Lake Rhona sits in a pretty neat geological place. From an aerial view (i.e., check out Google) it is contained within a large folded structure. These structures are from the Tyennan Orogeny, which was a complex, multistage deformation event that affected most of western Tasmania (Crawford and Berry, 1992; Crawford et al., 2003; Crawford, 2005). The underlying rocks of Lake Rhona are Pre-Cambrian quartzites, like that exposed at Frenchman’s Cap (check out my post “A Tasmanian “bushwalk” to a sturdy Frenchman’s Cap” for more info on them). They belong to the Tyennan block, equivalent to the Rocky Cape Group in the northwest (which has seen less degrees of metamorphism). The quartzites aren’t seen at the lake, but the beautiful white quartz sand is derived from these rocks.
The lake itself is a tärn (or corrie loch), which is a small bowl-shaped pool formed in a cirque (i.e., an amphitheatre formed by erosion via glaciers). The surrounding mountains of Lake Rhona are eastward-dipping conglomerates. In particular, they belong to the Owen Group and are mostly a fluvial to shallow marine succession that was derived from uplifted Precambrain quartzites in the Ordovician. The conglomerates make up the peaks that surround the lake, such as Reeds Peak (1290 m) and Bonds Craig (1260 m). This peak make a fun day walk to do at Lake Rhona, and since they are over 1100 m high they are classified as Abels (i.e., a classification of the highest mountains in Tasmania (i.e. over 1100 m), named after the discovered of Tasmania, Abel Tasman; check out “The Abel mountains of Tasmania” for more info).
Final thoughts
While it may be a long, tough and muddy walk to get there, the destination is definitely worth the effort. It’s pretty neat to be able to camp on a beautiful white quartz sand beach in the middle of the mountains with basically no one else there! Waking up in the morning and seeing the striking conglomerate mountains reflecting off the glass lake is truly breathtaking, and swimming in the lake after a long hike is quite the reward seldom given by mountain hikes. Lake Rhona is a neat and unique place in Tassie, and I had it on my list for a while. I snuck it in on my last days in Tassie, and it didn’t disappoint and was worth the effort and wait.
-Stephanie
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Lake Rhona. Another excuse for me to visit Tassie and buy a set of good boots.
Loved this blog – and the one before on the “Killiecrankie ‘diamonds.'” Am not even sure how I got on your mailing list, but am very glad I did. Have enjoyed it thoroughly, and want to stay on. You write very well, and your pictures are beautiful!
I’m not a geologist (though my uncle was), but have always loved rocks and geology, and read a good amount on it. Our interests do overlap at least to a degree; I and my family have been active “rockhounds” for close to 30 years, ever since living next to the Nipomo agate fields just north of Santa Maria, California.
Tried to ask you a question after the Killiecrankie blog, but then something went weird with my email (either my phone or server erased all but a few of the emails), so I don’t know if it even got to you, or maybe got caught in the wipeout. My son and I found a small, roundish, fairly clear “something” on one of our last hikes out in the country from here (southwest Wyoming) last Fall. Noticed that when we laid it on a lined paper, the image of the line was offset (jumped from near the middle to the upper part of the grain). The line wasn’t doubled, just offset. Can I ask if you’d have any idea what that could be? Hunted the Internet but with no success ID’ing it.
Looking forward to more of your blogs, and wishing you success in your career. (Are you still working on your Ph.D. or do you actually have it now?)
Hello Pete,
Thanks for the comment (weird it wasn’t working on the “diamonds” post). I’m glad you are following along with my blog (however it happened haha). It must be quite pretty in the fall in Wyoming I imagine 🙂
So, in regards to your question, I think I might know what it was… If the object you collected was clear and well rounded, as a pebble, it was likely quartz (should be pretty hard, a knife will not scratch it). I was going to suggest the thing you witnessed was a special property called “birefringence”, which is common in calcite. This is when regular light passes through the mineral, it splits in two waves, which will travel at slightly different speeds and are polarized at different angles to each other. Thus, the image you seen is duplicated and slightly off-centred. However, because the line was only off-set and not doubled, then it was just refraction of light through the mineral. When light passes through a different, denser medium (e.g., from air through mineral, water, etc.) it is slowed down. This will result in the image appearing at a different angle. There is a famous formula known as Snell’s Law which describes this.
Anywho, hope that helps and sorry for the long-winded answer!
I hope you continue to follow along with my blog and thanks for the good wishes. I still have to wait for my examination and edits on my thesis until I officially get my PhD, but it should be soon I hope!
Cheers,
Stephanie
Hi Stephanie,
Thanks for your reply and the info. From Canada and studied in Victoria? Interesting – I lived in Seattle for awhile. Never got to Victoria (which is my biggest regret from that time), but visited Vancouver several times ( and have a cousin who now lives across the Strait from Victoria, in Sequim).
You did a very good job of explaining your arnswer to my question clearly. Thanks! Can I toss one more your way? Imagine my son looking through our microscope at samples we collected from stream beds (we do tbis almost everywhere we go.) The light is on the left side of the scope, shining across. In several samples from the same ares, he sees tiny dark crystals, which he first assumes are just some kind of black sand. But then he notices that the light is passing through the crystal, coming out the right side. And that when he turns the crystal (which is only about 1 mm across), the color changes. Usually the emerging light is yellow in one position, and anywhere from orange to red wben turned. (He showed me one where the emerging light was yellow, then became very dark red when I rotated it.)
Any guesses? It was certainly intriguing. First time I’d seen that.
Thanks again, and I’m looking forward to your next blog. – Pete.
Thank you Stephanie, for taking us somewhere we would never have seen otherwise and your explanation of everything was great, Derrick and May, Hawaii.
Hey Derrick and May! Happy you liked my post and are following along! Glad I can share a bit of this place with you two. Hope you both are doing well and all is good in Hawaii (lots of amazing landscapes and geology there too)! Cheers 🙂 -Stephanie
Hi Stephanie, thank you for the report of the geology and pictures from this beautiful
lake! I can recall the ” Tärn” as a Quaternary name for a small lake in a morän terrain,
in my old country Sweden! Cheers from
Your Aussie Swedish geologist.
Hi Gunnar, thanks I’m glad you liked the post (both the text and pictures) ! Yes I’m sure Sweden has lots of similar glacial-formed landscapes and features like this tärn. I’m honoured to have made your day with my post 🙂 Thanks for reading and hope you continue to follow along with my blog, cheers! – Stephanie
Hi Stephanie, this looks absolutely fantastic!
What a pearl of a place. I remember Tärn from
the Quoternary in my old country Sweden!
I t would be hard for me to get there in person.
You have made the day for an retired geologist!
Stunning! Thanks for virtually taking us readers along.
Thanks, I’m glad you enjoyed the post and thanks for reading 🙂
Awesomeeeee!!!
I have to come back there to hike this mountain and swimming in the lake!!!!
Haha, yes you do Billy! 🙂