Pangea Day – where was your bedrock?
Following the lead of Chris at goodSchist and Callan at NOVA Geoblog, below is a snapshot of global paleogeography during the Late Triassic – just before the supercontinent of Pangea broke up – and where I sit right now on that map (small red circle). All images on this post are from Ron Blakey’s (Northern Arizona Univ.) fantastic website of paleogeographic maps and globes.
I’m in the San Francisco Bay Area of California and, as you can imagine, it is quite difficult to pinpoint the area. Much of northern California was in the process of getting accreted onto the continent. Central and southern California is even tougher to place precisely because of more recent San Andreas right-lateral movement.
In addition to the global maps, Blakey has created some zoomed int a bit to North America. This is Late Triassic again (~210 million years ago). The subduction zone that developed on the western margin of the continent during the Mesozoic is getting going around this time. Where I actually sit right now was probably offshore somewhere.
Check out these maps and give it a shot!
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In case you’re wondering what prompted this meme – this past weekend was a global event called Pangea Day, meant to bring people across the world together through film.
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Clastic Detritus 
Yeah, being somewhere in Nevada, which didn’t exist back then – well, there were some accreted terranes, but it’s hard to tell exactly where they are on that map – I’ve made up one kind of like yours, but with a much larger circle. Could be on land, could be out in the ocean somewhere! I’ll post it later when I can make some links.