eli5: Do you have to carve Fossils out of the stone or will they pop out in the form they are in, when the stone it split open?
In: 8
I’m not an archaeologist but I’ve been on a couple of fossil trips with an old professor of mine in East Tennessee, a hot spot for small marine fossils (used to be an ocean).
It’s a little bit of both in my admittedly little experience.
There will be cracks you can look for, edges of a shell, or something familiar- it takes a little bit of work to “get in the zone” and recognize patterns of what you’re looking for. *do research on the area you’re searching so you know what to expect* We we’re looking for sea urchins, nautiloids, maybe a starfish (personally) to take back to the lab and examine. Sometimes you can tap the fossil in rock at the right angle and it’ll split in half, then you can delicately chip away, and they have all sorts of dremel tools as well.
It’s definitely a skill set, I ruined several fossils trying to do it right.
It depends on the type of fossils, some fossils are found in sedimentary rocks where the rock is formed from layer after layer of deposits which are then pressed into forming rock. This type of rock can then fracture down the length of the layers revealing anything that was immersed in a layer so things like trilobites can be found by fracturing rocks. Larger dinosaur bones generally need to be carefully “dug” out of the other rocks around them often with special tools to prevent damage to the “bones” https://youtu.be/d5hV08h4aGA
Yes and yes…sometimes. But most of the time, for anything larger than a cat…the rock is prepared and shipped to facilities where it can be worked on in a protected environment. Smaller fossils are often left in their respective material, but are cleaned up and exposed for study or presentation. Some fossils can come from extremely soft material that is basically compacted sand, or like the ones from La Brea, in tarsands.
Hi!
I have a fossil bed near my home with many fossils from the carboniferous period in sedimentary rock.
These plants have been carbonized (turned to coal or a coal like substance) while trapped in these layers of sand and mud that have been compressed to form sedimentary rock.
It is possible to use tools to cleave the rock. Sometimes this works well to display the black image of the plant. Other times this makes a mess (probably because of my lack of skill or training).
Fossils with animal bones are from different time periods and may have different characteristics.
Hiii 🙂
As it was already mentioned- it indeed depends on the fossil as well as on the matrix (the rock, sediment) that contains it.
There are many different techniques of fossil preparation, I can briefly describe some for you 🙂
The majority of fossils are found in sediments. In unconsolidated sediment (sand, clay, ash) you can find “free” fossils and some of them you can even safely take out- I work for National Museum in Prague and I usually pick out microfossils from caves’ sediments. Even though I just take a tweezer, pretend to be a Cinderella and carefully pick fossils out (tiny rodent teeth, vertebrae, leg bones etc.) the sediment is usually rinsed and dried in advance in order to get rid of the mud and clay particles. However, you can say that they just “pop out in the form they are” from these kinds of sediments 🙂
Sometimes though, big bones can be found in unconsolidated/ semiconsolidated sediment. These are usually too fragile to “just take out” so paleontologists usually create a plaster or burlap to wrap the fossil with the surrounding sediment in. This technique also protects the fossil during transportation. The plaster is then taken to the fossil preparation lab where it’s opened and worked on- either with paint brush, dental pick or even airbrush.
There are also many ways and techniques to consolidate the fossil prior to the preparation if it’s too fragile or fragmentary. For that, different types of glues and consolidators are used.
Most of the sediment is however, compressed into rock over time. Then there are two preparation options available. Mechanical and chemical.
Mechanical preparation is the most common method. Various tools (dental tools or air- powered micro jackhammers) are used to chip away the surrounding matrix while carefully exposing the fossil. Again, the fossil can be strengthened in advance, which helps it to be more resistant to the vibrations of preparation tools.
Chemical preparation is used when the fossil and matrix are composed of different chemicals (for example silica fossils in limestone). In such case, surrounding matrix can be easily dissolved without any damage to the fossil.
Anyway, if you just want to look for fossils yourself, I am sure you can find a place in your area where they just pop out as they are 🙂
I wanted to end this small overview by uploading some photos of the fossils I prepared, but apparently it is not possible here on Reddit ( I am new here) 😀
Hope I did your question justice, have a great day! 🙂
I have not done this myself, but I used to have a couple of friends that did this stuff.
In my area, when a construction project hits fossils, they have to stop and let a local university have some time to examine the area and remove anything of interest. Around here, the fossils are mostly sea creatures and not that interesting to the universities.
After they are done, they will let locals go in and remove fossil matrix for their own collections.
When they were cleaning up the fossils, they would chip away some of the stone. The rest of the stone was removed using Muriatic acid brushed on to the stone. The acid would typically dilute before it started attacking the fossil materials.
So, with a combination of chipping, acid, brushing and a few other mild abrasive techniques, they would clean the fossils out of the matrix.
Sometimes fossils are harder than the surrounding rock and in that case they’re right there on the surface.
Latest Answers