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Valentine’s Day Archaeology Style

Everyone likes to bring up radiocarbon dating for this Hallmark day of love. There’s other kinds of dating we archaeologists use too!

We’ve also got…
Obsidian hydration dating
Tree ring dating (dendrochronology)
Type dating (seriation)
Potassium-Argon dating

The list goes on, my friends! I’m sure you’ve heard the joke “Archaeologists will date any old thing.” It’s true. As a group, we looooove to get dates. Dates are closer to concrete answers. We may never have absolute answers, but we really like to get close to them if possible.

Here at TOA, we have Origer’s Obsidian Laboratory. Guess what we do there? Yep, it’s an obsidian dating service. Flakes and projectile points alike flock to our lab to get a date. We cut, grind, and slip pieces of obsidian between glass to read hydration bands. Go check out our Lab’s page to learn more.

Tree ring dating helps calibrate the ever-so-glamorous carbon dating system. Most people have at the very least heard of radiocarbon dating, but few knew that the simple act of counting tree rings helps calibrate something so obviously scientific.

Dating by types, known as seriation, is a form of relative dating that compares items based on where they fit into the known order of manufacture. I assure you, it has nothing to do with dating your Aunt Sally. Let’s say you’ve three projectile points that are from the same site, but shaped differently and found at different levels. You can correlate their age to the type based on the levels they came from (assuming the site is undisturbed of course). That’s thanks to the law of superposition, which tells us that the top level is the youngest and things get older as we go down into the ground. Once you know the seriation for projectile points (or any other type of artifact) in an area, you can perform this type of relative dating!

Potassium-Argon dating is used on fossilized human remains. It isn’t done much around here, but is popular elsewhere. In practice, it’s much like radiocarbon dating since it deals with measuring the product of an isotope’s decay in relation to its half-life.

So there you have it, folks. A brief look at some other forms of archaeological dating!



A note on Paisley Caves

Paisley Oregon is known for a couple of things; their annual mosquito festival, and Paisley Caves. With the co-operation and support of the Bureau of Land Management, the University of Oregon has built an international team of scientists to study the archaeology within the caves. Origer’s Obsidian Laboratory has been working with this team since 2005. This summer we returned to the caves to work on on-going research regarding obsidian hydration in cave environments.

For those who haven’t heard of Paisley Caves, it’s a pretty exciting site. Several finds in the site suggest some of the earliest human occupation in North America. What has probably received the most publicity are western stemmed projectile points and coprolites that have human DNA dating to about 13,200 calendar years ago.

Our involvement has been in looking at the obsidian from the site. More specifically, we are exploring the issue of how the cave environment influences the development of hydration bands. Our original analysis provided some counter-intuitive results; for example the interiors of the caves were typically cooler at noon than at midnight. Why? The caves face generally west, and get little sun before mid-day. From noon until sunset they get full exposure and the rock absorbs heat. From sunset, through the night the heat is radiated into the caves from the rock, pretty neat.

Our current research is geared at understanding what happens in the caves in three dimensions. We have deployed about 100 temperature sensors to establish what the temperature is doing at various depths, and from the front of the caves to the back. With those data we will be able to see what is happening with the temperature, which will help us understand the hydration measurements, which will help understand the dating of the deposits in the cave.

Many thanks to Dr. Dennis Jenkins of the University of Oregon for allowing us access to the work site during his field schools. That kindness has saved us hours, and given us a chance to meet his amazing students, who work cheerfully through some tough and demanding circumstances.


How do you thank someone . . .

On August 28th 2012, Dave Fredrickson died. This won’t mean much to many of you, but for us here at Tom Origer & Associates, it was a major loss. His wife, Vera-Mae, died about a year ago, and I think he was ready to join her. She was a formidable woman, and the two of them were a wonderful balance of personality and presence.

Dave was our teacher and mentor in archaeology; for some of us starting in the ’70s, for others the ’80s, ’90s and in to the new millennium. I took my first undergraduate field methods class from Dave, and my first graduate seminar, as well. He was a touchstone of stability and science when we got off on wild rabbit trails. And no matter how young or old, he treated each of us as colleagues worthy of his respect.

I have been trying to write this since he passed, and I have been stumped. The things that made Dave special to me as an individual, I am not inclined to share in the blogosphere; everything else is almost generic ‘good person’ wording that one expects in referring to the dead. So I am struggling to walk a line.

Perhaps one of his most amazing characteristics in a world of off-hand talk, is that I never in 30 years heard Dave say anything bad about another person. He didn’t like everyone; but the worst thing I ever heard him say was that he was grateful to Martin Baumhoff for accepting him at UC Davis, because there was someone at Berkeley that Dave could not comfortably do his graduate work with. Not exactly brutal condemnation.

We knew Dave best as an archaeologist, but he was an almost infinitely complex person. He was an accomplish folklorist and musician with an extensive collection of traditional song lyrics acquired from years of talking to people about old variants of different tunes. If you ever wondered who watered the plants in the median on the freeway, Dave did that (for a while). He was an avid recycler, a quilter, artists’ model, cab driver, and more avocations that we are just now learning of as those who love him share their memories.


Post- SCA Annual Meeting wrap up!

And suddenly, it was April. This past weekend was  the Society for California Archaeology Annual Meeting down in (somewhat) sunny San Diego.  From across the state, archaeologists descended upon the Town and Country Resort to hear what their colleagues have been up to for the last year.

The meeting began Thursday night with the opening remarks and Plenary Session. The Plenary Session’s topic was Genealogy, Theory and Practice in California Archaeology. Society members spoke about their theoretical and practical genealogies – about where and  from whom they learned this trade we call archaeology. Everyone’s trajectory into where they are now varies a great deal, but one thing is common throughout – the circumstances of our learning shapes us in many ways that you might not think about until asked to speak about. It seemed like a few of the speakers learned a lot more about themselves through this explorative exercise than they thought they would. This is the case whenever the lens gets turned back onto the one normally looking out through it. Exercises like this are good to reground and understand literally where you are coming from, what framework you are working in. It is through understanding this that we may understand others and potentially avoid major schisms, because once you understand where someone is coming from, you tend to take what they have to say on a different level, and try to make sense of it rather than throw it out with the bath water just because you disagree initially.

Friday the main sessions and symposia began with, as usual, a wide variety of topics to choose from. Anywhere from current research on the archaeology of fishing in California to archaeology of the Great Basin and Eastern California and on to the mysteries of San Diego’s Presidio. I was at the registration desk Friday morning, making sure attendees got their badges, the schedule, and their special event tickets before releasing them into the conference.  Friday night was the special event everyone looks forward to (I’d say the most) – The Reception and Silent Auction! This year it was held at the San Diego Museum of Man in Balboa Park, and I hear it was a real hoot. The socialization of archaeologists who may not have seen each other since last year in a museum with food, drink, and cool items to bid on is really something to experience.

Saturday continued the major sessions and symposia with topics ranging from the Fort Ross Bicentenary to Contributions to Southern California and Channel Island Research in Honor of Dr. Andy Yatsko and on to a symposium put together by one of my fellow grad students at SSU (now a MA holder) on the Diverse Research in a Diverse Region: Studies in Northern California Archaeology and CRM. Saturday also included the general poster session in the book room, with many, many topics covered. The Student Affairs Committee held their student meeting and mixer, which I attended and felt was really valuable. During the student meeting, the Padons told us about the  California Archaeological Site Stewardship Program (CASSP) and how the volunteer stewardship work is a great way to get experience for those without, and Anmarie Medin from the California Department of Transportation (Caltrans) explained the process for getting a job as an archaeologist with Caltrans. The formal banquet was held Saturday night, with Ian Hodder as the guest speaker. He gave a talk on entanglement theory, which is the topic of his forthcoming book.

The half-day Sunday of any conference is always a bit of a wrap up day, but there were still many interesting talks that morning. A lot of the historical archaeology presentations were held, along with Island and coastal archaeology, and the archaeology of Southern California. As everyone went their separate ways to start heading back home, words of farewell and the promises of emailing this or that article filled the air… until next time!



Making Connections

As the year continues to seemingly zip by, it’s nearly March! In fact, it’ll be here tomorrow. Today is a day that only exists every four years. In the intervening years we pretend our calendar makes sense, but that’s another story for another blog.

Speaking of calendars though, the Society for California Archaeology Annual Meeting is coming up fast! At the end of March, Archaeologists (and other friendly people interested in the field) from up and down the state will be gathering in San Diego to share research, ideas, plans, and reconnect with each other. Panels and presentations abound during the day, and by night we get our social networking on– the real life kind (but I’m sure some of us will tweet or status about it).

Last year, the SCA Annual Meeting took place in our neck of the woods, in Rohnert Park and our office was in charge of local arrangements, which means we had a lot to do in order for the meeting to run smoothly. We had to coordinate with the hotel conference venue, plan the silent auction, run the silent auction/party, and coordinate the volunteers among many other little things you don’t think about until you’ve got to put something like this together! As a matter of fact, I was the Volunteer Coordinator. Let me tell you, coordinating volunteers of any kind is much akin to herding cats. No offense to any of my volunteers, but juggling the schedules of 25 people for a conference a few months down the line through spotty emails is quite the challenge.

This year, I am again volunteering, but this time as one of the cats being herded. We’ll see how this year’s coordinator manages things! I do wish her luck, and I’ll do my part to help ensure the meeting runs smoothly. Without the volunteers, the meeting would have a very difficult time!


SCA logo

You Archaeologists Dig All the Time, Right?

Let’s play a game!

I say “archaeology” you think of…?

Indiana Jones fighting Nazis and recovering things because they "belong in a museum!"

Digging lots of square holes in the ground

Digging and Indiana Jones, am I right? Perhaps even *shudder* dinosaurs?

Well, these days a lot of the archaeology done in the United States (especially in California) is not the digging kind, and usually not for purely academic purposes either  (and NEVER the dinosaur kind, since that actually falls into the field of paleontology). Most of the archaeology done is contract compliance archaeology, meaning that it is being done to comply with the laws and regulations. Which rarely means digging.

We do surveys of land looking to be developed to see if there is any surface evidence of archeological remains.

We do research on the properties and the people who lived there in the past.

We monitor ground disturbing activities at sensitive locations and document any archaeological finds.

We read and write lots of technical reports.

We study the hydration rate of different sources of obsidian. (Our office does, anyway)

We create management plans for known cultural resources (archaeological sites, historic buildings, traditional cultural places) which involves assessing the resources for significance under the law, which sometimes results in the development avoiding the resource altogether, capping the resource to protect it from damage, and a whole slew of other options! Digging actually becomes a last resort when a resource can’t be avoided or protected in some other way; when a developer is set on a location, the best way to lessen the effect on the resource is to record it in the most thorough manner we know- digging it up and writing every little detail down!

This is just a brief touch on all the things we do as archaeologists. Who says we can’t do it all?

And so, it begins…

As we begin our journey around the sun this year, so begins this blog.

This blog will be a collection of tales, essays, presentations,  stories, jokes, photos, and SO much more related to archaeology and history as seen and experienced by the people who make up Tom Origer & Associates. Check us out at to learn more about our firm and the services we provide as cultural resource managers.

Some of us here at the office thought a blog would be a great way to disseminate knowledge, begin dialogues, and make ourselves known. Plus, hello, bandwagon! The Society for Historical Archaeology just began a blog, the Archaeological Institute of America has a blog (incidentally, I came up with our blog name before seeing theirs) , Terry Brock does all sorts of blogging and social media. It’s a great way to interact with peers and the public.

The whole idea of blogging is a new concept for some of our staff, so things might be a bit slow at first, but I practically grew up on the internet, so I’ll make sure we get this thing going! We would also love to hear what you have to say, about our posts, about our field, about us!

Here’s to 2012 and the broadening of horizons, cheers!


What kind of things would you like to see in future posts? Comment below or send us an email at