A series of Questions for our Geologists.

If it gets people interested in geology, Google Earth is a good thing, Jar. What you're looking at are Cretaceous rocks (the arc) that separate the southern Appalachians on the east from the Mississippi Embayment on the west.The following link should help: The OuachitasEd. To fix geography.This message has been edited by roxrkool, 01-15-2006 12:00 AM

Im getting a little out of my league here, but I'll take a shot at it.The Appalachians/Ouachitas/Ozarks are formed from several orogenic events culminating when the North American continent collided with Africa and South America a couple hundred million years ago. Following that collision, they began to wear down from erosion.Sometime later (just prior to the Cretaceous), the three continents separated via rifting and the Mississippi Embayment formed as a reactivation of a previous rift zone (though I'm not sure if that was a failed rift). Since the NA continent didn't split along the MS Embayment, it's considered a failed rift zone and this is the reason for the New Madrid Seismic Zone.When rifts form, however, the ground starts to subside until eventually the ocean is allowed to inundate. So this likely happened in the embayment to some degree, but also, during the Cretaceous, sea level was rising and so the failed rift/embayment was inundated with marine waters. This sea level rise also formed the Western Interior Seaway from Texas, through Colorado/Nebraska, and up into Canada. When sea level decreased, the embayment became a major drainage basin.The arc is likely an artifact resulting from the erosion of the Appalachian highlands, deposition of Cretaceous sediments against the highlands, uplift, and finally erosion by the Mississippi River.Hopefully coragyps or edge can confirm or correct the above. I believe they are both quite familiar with the area.This message has been edited by roxrkool, 01-18-2006 09:03 PM

You're welcome. It's one of my favorite.

Any pictures, jar?

I can do a search on GeoRef if you give me some specifics such as geographic names or mines in the area. Unless a general search on "Ecuador" or "Northern Andes" is fine with you. I can then export them into a text file and post here or email them to you.

Is it a plunging anticlne, edge? It has the right shape (pointy on one end), but the flat-lying geology is odd. Unless it's not exactly flat-lying. I couldn't find any structural data for Chandler Mountain, AL.Here's an image of the Sheep Mountain anticline in Wyoming and I thought perhaps it was somewhat similar, minus the flat-lying geology: This message has been edited by roxrkool, 02-07-2006 04:52 PMJust wante to add a link. There are some fabulous structural images HERE showing the significant influence of structure on topography.This message has been edited by roxrkool, 02-07-2006 04:57 PM

Ah, I should read up on the Valley and Ridge province a little more. Even the surrounding geology and structure makes it look a plunging fold. Neat stuff.Good talk at dregs? Is that the Christmas party you went to?At work, we recently got the news that we will be returning to minerals research. No more (or very little) environmental stuff. Another swing of the pendulum... but hopefully not the axe.

Okay. If it's in the Tabacundo area of Ecuador, I only found one reference anyway, but it did mention pumice beds. Let me know if you need something else. Cheers.