Anthropocene! Naming a new geological time period after ourselves certainly has a nice dramatic ring to it, even if it smacks of the hubris that got us into our current climatic mess in the first place. But can our species, as The Straigraphy Commission of the Geological Society of Londo claim in the GSA Today paper that everyone is talking about (update: Brian and Greg has also contributed enlightening perspectives), really justify claiming a place on the geological timescale?
There’s geovandalism – and then there’s sheer f***ing insanity.
Thousands of pre-dinosaur fossils are scattered in the rocks of the Guryul ravine, rated by geologists as the world’s premier site for the study of species from the Permian period (299-251 million years before our time).
These species, felled by the greatest mass extinction ever, are being wiped out a second time.
The most fossil-rich stretch, a little over one square kilometre, houses five quarries, two of them operating now. A large part of the extractions is supplied to cement factory owners at nearby Khunmoh.
Not only is this apparently one of the more complete stratigraphic sections across the Permian-Triassic boundary, but it’s location in Kashmir means that it hasn’t actually been studied particularly well. And they’re turning it into cement. Cement! Words actually fail me. Polite ones, anyway.
A vast array of suggestions were put forward for the identity of the dome-like structures in Friday’s geopuzzler, including lava tubes, folds (both pre-and post lithification) and Arrakian sandworms. How I wish the latter were true…
Anyway, smug points go to those of you that figured out that we are in fact looking at some some impressively large domal stromatolites – layered carbonate structures precipitated by algal mats. These ones are much older than the Namibian ones that I’ve blogged about previously – a good two billion years older in fact. As Greg correctly speculated, these are from the lowest part of the Late Archean to early Proterozoic Transvaal Supergroup. During this time, a large shallow marine platform extended over much of South Africa, which provided a very welcoming home to reef-building cyanobacteria (thanks to some preserved bacterial microfossils we know these particular stromatolites were definitely biological in origin).
That’s worth considering for a minute: for at least two billion, and possibly 3 billion years of the Earth’s history, the algal mats that precipated stromatolites such as this were pretty much the only macroscopic expression of life. We might think of Precambrian ecology as ‘simple’ compared to what followed from the Cambrian onwards, but in fact we find a great diversity of stromatolite forms and sizes, each adapted to different environments and conditions; perhaps things weren’t quite as ‘simple’ as we tend to imagine.
Not only did everyone seemed to enjoy the big crater debate, but there were also suggestions in the comments that more conundrums of this ilk might be make a fun companion for What on Google Earth (which I never seem to actually see before someone’s solved it nowadays – darn time zones). It’s worth a go, anyway, although it might take a while to get the format and level of difficulty right…
This week, I’m asking: what is the origin of the structures in this photo (click for a larger version)?
Let me know what you think in the comments.
When I was out in New Zealand doing fieldwork for my PhD, I spent most of my time based in Gisborne, a sleepy little town on the east coast of the North Island. Over Christmas, it seems that Gisborne was shaken by a strong (magnitude 6.6) earthquake. It’s quite weird seeing pictures of damage to buildings I recognise – for example, I’ve bought stuff from this store:
