Ediacaran

Geology Photo of the Week # 18 – Jan 13-19

Matt Herod January 14, 2013

The photo for this week is something that I stumbled upon the other day when looking for directions to a friend’s house. It is a large scale concentric feature on the landscape and is located about 40 minutes north of Kingston near the hamlet of Holleford. I have actually been to this location in person when I was a geology undergrad and so I had the benefit of prior knowledge to help me interpret this feature. However, the person who discovered the feature, using aerial photos in the 1950’s did not. Try to guess what you think this could be?

Well, have you thought about it? It is actually an impact structure left behind from a meteorite impact. It was first identified by Dr. Carlyle Beals using air photos and has since been the subject of geophysical study and drilling by the Geological Survey of Canada that has confirmed its identity as an impact feature. It is about 2.5 km in diameter and only 30m deep as it has been extensively eroded by glaciations since its impact about 550 million years ago in the Ediacaran. Nonetheless, the topography still remains and the geophysics confirm it. The geophysical surveys showed gravity and magnetic anomalies and drilling found evidence of shocked quartz, which is a smoking gun for meteorite impacts.

I think it is pretty cool that features like this are visible in Google Maps/Earth and available for anyone to discover or rediscover in this case. I imagine that there are dozens or even hundreds of features like this around the world that have not been discovered yet or realized to be impact related. I expect there is still room for exploration now that tools like these are available to everyone and could shed light on the tortuous history our Earth has experienced.

Cheers,

Matt

Geology Photo of the Week # 16 – Dec 16-22

Matt Herod December 17, 2012

It’s photo of the week time! I hope you’re excited…I am! There has been a lot of consternation in the twitterverse and geoscience community lately about the true identity of the Ediacaran biota, particularly the little guy pictured below. The abstract can be found here. The basic proposal is that the Ediacaran fossils are not marine, but rather are actually lichen.

Dickensonia specimen at the Smithsonian. (Photo: Matt Herod)

Bonus photo of the week. This is the closest I’ll ever get to being in Science….for a long while at least.

Cheers!

Matt

Geology Photo of the Week # 10 – Nov 4-10 – A Mysterious Monster!

Matt Herod November 5, 2012

I apologize for the delay posting this. I was in Washington DC earlier this week to take in a Supreme Court hearing that never actually happened due to Hurricane Sandy. My flight out was also delayed and thus many other things in my life are delayed right now including this post.

This photo poses a bit of a conundrum…since I don’t have a clue what it is! I have an idea, but I’d like to get other opinions as well. I apologize for the poor quality of the photos. I had to climb up a 5m cliff and then take the photo of the overhang above me at full zoom with my little point and shoot. The rock is a reddish sandstone and is the bottom of a rippled bedding plane. You can kind of see the ripples at the right side of the photo. As for scale I don’t have an exact one but it is approximately 10-15cm long and 5cm wide. The location is the southern end of the Flinders Ranges in South Australia, about an hour’s drive north of Port Augusta (see the map below).

So here is your challenge: what do you think that oval-like shape is? It appears to be a fossil of some description, but what is it? I am not ashamed to admit that I don’t know. Please guess in the comments section below.

(Photo:Matt Herod)

Approximately where I was staying just north of Port Augusta on the sheep and cattle station of some friends. The Flinders Ranges are just to the east.

As I said I have a suspicion what this could be although I am not sure. I believe it is an Ediacaran fossil that dates back between 635 and 545 million years ago. Indeed, the Flinders Ranges are home to a little village called Ediacara only a few hundred kilometres north of where I was and the namesake of the Ediacaran.

I suspect that these impressions are possibly of the Ediaracan creature Spriggina or maybe Dickinsonia? It appears to have bilateral symmetry and is reasonably large and ~10 cm long and 5 cm wide.

Spriggina Floundensi (Image: Wikipedia)

The other possibility that I have been considering is Dickinsonia. Dickinsonia is classified as likely an animal of an unknown kingdom. Regardless of its affiliation, or lack thereof, it also has bilateral symmetry and can be quite large. Indeed, the species D. lissa has been found up to 15 cm. It can also have similar morphology to my mysterious fossil as D. lissa can have an elongate shape.

Dickinsonia species and their morphologies. (Image: Wikipedia)

So I leave it to you to figure this out. Please let me hear your opinions since I certainly am no paleo expert, but I’d love to get to the bottom of what this mysterious fossil is.

Thanks for reading,

Matt