Friday, May 31, 2019

Fossil finding fun!

Softball-sized concretions hold treasures

You never quite know what you’re in for when you work at the Port Townsend Marine Science Center. Sometimes, the day will get totally away from you - and you just have to go along for the ride.

As part of our responsibilities for the Marine Mammal Stranding Network, PTMSC has been tracking a deceased gray whale first seen floating off Indian Island at the beginning of the week. On Tuesday, we got a report that the whale had landed in our response zone and so little time was wasted before a crew of staff and AmeriCorps were piling into a car and driving out to respond to the stranding.

The particulars about this stranding are still being pieced together, and will certainly warrant its own blog post once more information comes to light. For now, I’ll end this part of the story by saying that gray whales are having a particularly rough year up and down the West Coast. More information on the current increase in gray whale strandings can be found here.

But here’s where the day took a sharp turn toward the unexpected. (And, yes, I recognize that getting to see a gray whale up close is the “expected” part of this story. Such is the life of a PTMSC AmeriCorps member.)

As we were packing up our stranding gear and getting ready to hike back up the bluff, I glanced down and saw - lying in a pile of dull, unassuming beach pebbles - a dull, unassuming, but perfectly spherical rock.

I was immediately suspicious. I pointed it out to Citizen Science AmeriCorps Michael Siddel, and then again to Education Coordinator Carolyn Woods, and then (for good measure) Citizen Science Coordinator Betsy Carlson.

We all agreed: this softball-sized rock was a concretion.

Dull and unassuming, concretions stand out only due to their shape. They are almost perfect spheres!
Take a fresh piece of prehistoric plant or animal, bury it in sediment, let it cook for a few years, and eventually that piece of organic matter might become the center - or nucleus - of a concretion. Today, these orb-like formations are harder than the surrounding rock, and so are easily eroded from our bluff faces and deposited on our beaches. Crack one open, and that organic nucleus is still there - a fossil, in a perfect geologic gift box!

Once we spotted one concretion, we started noticing that the stretch of beach we’d been working on was littered with them, ranging from baseball- to soccer ball-sized formations.

So, like good scientists, we got cracking.

One of the best fossils of the afternoon, found by the beach's landowner. Check out the carapace on the crab in the center! Photo by Betsy Carlson.

In a few short minutes, we had quite the collection going. We found fossilized snails, wood fragments, leaf impressions, and one very nice crab. It had quickly turned into an incredible learning opportunity for the landowners who had initially reported the stranding - they had no idea their beach was full of potential fossils!

Eventually, we left the landowners to their newfound hobby and went a few miles up the road to two of our stranding network volunteers’ home. Our intention was to explore potential necropsy sites for the gray whale (again - more details to come in a later blog post). Of course, Michael and I were immediately distracted when we started seeing even more fossils on this stretch of beach.

Checking to see if any fossils were exposed after
a few good hammer smashes. Photo by Carolyn Woods.
This time, we were prepared. We brought a hammer.

An hour or so of rock smashing later, we found more wood fragments, leaf imprints, and a handful of additional shells. We even found a few non-concretion fossils, embedded in large boulders at the surf’s edge!

All in all, it was a pretty spectacular day. Getting to see a mature gray whale up close was one of those awe-inspiring moments that will last a lifetime. And the fossilhead kid in me - who happily watched Jurassic Park on constant rerun throughout her childhood - is having a blast trying to identify some of her fantastic new paperweights.

Another incredible find: a marine snail shell, preserved in a
rock totally exposed to the beach! No concretion needed!

Written by Ellie Kravets, Natural History AmeriCorps Member 

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