Wednesday, December 7, 2011

What is this??

The point of this post is to get you to give me your input on what you think the picture below is. First though, a little backstory...

A few years ago I was on vacation in Australia with a friend. We were travelling around the country and trying to see as much of it as we could. We both felt that a visit to Australia was not complete without a visit to the outback. Luckily, my friend had made some contacts on a previous trip for a school exchange. Therefore, while we were in South Australia we took the bus north to meet up with a friend whose family lived in the outback on a large sheep station about an hour north of Port Augusta, South Australia.

The station was a beautiful place. Wide open spaces with a huge mix of landscapes such as desert, salt flats and the foothills of the Flinders Ranges literally in the backyard. On top of this it was once of the most varied geological environments I have ever visited. All in one small area were limestone beds containing beautiful stromatolites and ripples interbedded with microbial mats.


Ripples and microbial mats
In addition to these awesome features the station was also home to giant kangaroo bones from the Pleistocene. 
The foot of a Pleistocene kangaroo

The ?femur? of a modern kangaroo being held next to that of a Pleistocene kangaroo.
Aside from the great geological attractions of the station were archaeological curiosities as well such as this aboriginal arrowhead that I found laying in the ground.

Aboriginal arrowhead
However, I digress. The real purpose of this post is to gather your opinion on what you think the upcoming picture is of. I have my own theory, which I will outline below the picture. I apologize for the poor quality. The shape in question was on the bottom of a cliff face which I had to climb up to and then lean out to take a photo of with full zoom. You are viewing this in plan view so imagine a flat surface above your head that contains the shape and you are looking up to see it.

The rock containing the strange oval shape (~10cm) above is a sandstone and is the bottom of a bedding plane with apparent ripple marks. The red colour is due to iron oxide in the rock staining it red. Any ideas?

My theory, and I like to think that this could be the right one, is that this is a fossil of an extremely ancient organism called Spriggina. Spriggina lived in the Ediacaran, the most recently named of all geologic periods, which spans a time from 635 - 542 million years ago and was the period right before the Cambrian. 

File:Spriggina Floundensi 4.png
Spriggina. Scale is in mm. (Wikipedia) 
In fact, the name Ediacaran comes from the tiny village of Ediacara, located only a few hundred kilometers north of where I was, in the heart of the Flinders Ranges. Most of the fossils found in the Ediacara area can be seen on the bottom of sandstone bedding planes that contain ripple marks, which is one reason why I think that my picture could be some sort of Ediacaran biota. At least the depositional environment is right as well as the general shape.

The problem with my Spriginna theory is that the fossil in my picture is very large compared to Spriginna fossils that have been found to date which are around 3cm. Who knows though? There are other types of Ediacaran fossils that could also fit the description of this one and maybe it is one of these? Perhaps it is just a strange weathering feature and not even a fossil?

So that is it? What do you think the mystery structure is?

For more information on the Ediacaran see this link:


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