Backyard Sediment Sieving

Jen here –

Our department recently moved into a new building and our rock room is not yet set up! The rock room serves as the go-to room for getting messy within the department. This can vary by project – you can be cutting samples with the rock saws, polishing samples, or washing sediment. I recently collected a lot of sediment in 5 gallon buckets that needs to be sieved. Some of it is for a fossil summer camp hosted through the McClung Museum of Natural History and Culture. Since the rock room isn’t ready to be used just yet, I’ve started sieving in my backyard! Sieving is useful for separating out different sizes of fossils. It helps you find the very small microfossils and smaller pieces of fossils that may not preserve together.

Example of how I started sieving. I ended up moving all the buckets much closer together!!

I usually let the sediment soak in water for a few days this helps get dirt particles and grass off the rock. I can rinse it by simply pouring out the top part of water. I usually fill it up several times and knead the sediment while I do this. For this specific project I’ll just use 3 sieve sizes: 4mm, 2.5mm, and 1 mm. At the summer camp we will be focusing on the larger fossils that we can pick out with our eyes rather than the microfossils! I start with the bucket full of sediment and plop some of the wet slop into the sieve. I then pour water over the sediment and shake the sieve until all that is left in the sieve is the material that cannot fall through the mesh. I usually give it another rinse and then dump it out in the small bucket. Everything that was smaller than the sieve mesh fell through into the other 5 gallon bucket.

Once the original bucket is empty, you can swap buckets and go to the next sieve size! Since I’m trying to get this sediment pretty clean I will soak the smaller bucket in water and rinse it several times and then let it dry! Usually, I would be very careful to keep all the different sieve sizes separate but I’m going to recombine this sediment once I’ve given it a good clean. The summer camp students will re-sieve the material and examine their findings in each sieve size!

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