Optically Stimulated Luminescence Dating

[Kimberly Munro]

In a few weeks I will be working on a local dig here known as the Wakulla Springs Lodge Site. Wakulla Springs is home to one of the largest and deepest freshwater springs in the world, and is the place where all the old Tarzan movies were filmed (not to mention the Creature from the Black Lagoon) The excavations are sponsored by the National Geographic Society, and the site itself is believed to be a pre-Paleo period site. Several complete mastodon skeletons have already been recovered from the springs... http://www.floridastateparks.org/wakullasprings/

The purpose of my discussion though is the dating technique which will be used at the site. It is known as Optically Stimulated Luminescence Dating (OSL), and I have not heard too much about it. As far as I have heard, it is a relatively new dating technique, and this is the first time I have really heard anything about it. Has anyone else heard or worked with OSL dating, and if so, what were the results?

Here is the brief introduction on OSL dating that was given to me from the site sponsors: OSL dating is a radiometric method of dating that measures the radioactivity of quartz sand. When sand is buried, it accumulates a progressively increasing radioactive signautre, but when it is exposed to sunlight, its radioactivity is "bleached" out. The change in the amount of radioactivity can be used to date sand grains, and hence ,the age of associated materials. Luminescence dating can date contetual material that is only a few decades old to as old as 300,000 years.


Thanks!
-Kimberly

[jimbojames]

wouldn't know where to begin with that one. But, you sure do get some great dig experience. Peru, now this, wow!

[Michael]

The company I work for has used it. Only a few places in the US do luminescence dating. Utah State, Colorado Federal Center, University of Oklahoma I believe and University of Chicago. I don't know much about it aside from the fact that samples can not be exposed to light. Placing a duct taped or black sample tube against a unit wall and knocking the dirt into it is the method we used. Depending on the lab and the amount of samples it can anywhere from a month to a year to get results.

[mark a corbitt]

hello ,im from s. ga. and have been swimming at wakulla since i was a kid. big gators and mastodon bones, a magical place. i recently heard dunbar has 15000 b.p. dates. any scoop. how did the tsl work out? mark

[Kimberly Munro]

sorry for the late response, I don't come onto archeonet as often as I should!

Yes Dunbar gave a presentation a few weeks back and has dates of 18000 b.p. and more...he is waiting on publishing anything until he gets more testing done as he doesn't want to be stoned I think! It was an interesting site to say the least and a fun dig, I will definitely try to get on the next one if Dunbar goes back out there.
-Kimberly

[ShadyGroveAG]

I think that any interpretation resting upon OSL data must necessarily consider the formation processes at work presently and historically at the site. For instance, is the site known to have flooded in the past?

Sounds like fun...the way my dept. is funded here in AL, we're still rockin' farmer's levels!