Basic Coring Device: Components: Head Tube Cable Piston. HEAD. CABLE. TUBE. PISTON. The Head attaches to the top of the tube. The piston is inside the tube and attaches to the cable which runs inside the tube out the top and up to the people on the surface.
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The Head attaches to the top of the tube. The piston is inside the tube and attaches to the cable which runs inside the tube out the top and up to the people on the surface.
The piston starts out at the bottom of the tube. The coring device is lowered into to water down to the depth where we want to start coring.
The cable, with one end tied to the piston, runs inside the tube out the top of the device and to the people on the surface.
Once the corer reaches the start depth, the piston cable is tied up (or held onto very tightly as in this picture) by the people at the surface. This stops the piston from going down any further. Now the piston is right at the top of our core with the tube above it.
Now we are ready to start taking our core. With the piston still tied up at the surface, we push the tube down past the piston into the sediment. When we have pushed the length of the tube we stop, untie the cable at the surface and pull it all back up.
When the device comes back up, you can see the piston is now at the top of our newly collected core! In the tube above the core the piston acts just like your thumb over the top of a straw, keeping all the sediment below in the tube.
Some lake sediments are too stiff to be collected with a plastic tube. In this case we switch to using a coring device with a steel tube.
Here researchers use a similar coring device, but it has a larger steel tube with serrated teeth at the bottom. These teeth are used to cut through sediments that have a lot of plant material in them.
Sometimes small planes and helicopters are used to transport the coring equipment to remote destinations. It is important to think about the size and weight restrictions during transport when designing coring equipment.
Coring devices aren’t the only thing that may need to be improvised while in the field. Sometimes the coring platforms need to be made on site as well.
The weather can also be an obstacle when doing field work. It change very quickly forcing researchers to modify their plans.
Not all coring devices are pushed in with rods. For very deep lakes, like this one (~400m deep), corers are sometimes lowered on a cable with a winch. Here the corer is driven into the sediment by 600lbs of weights.
For very large projects, drilling rigs are used. These are more complex to operate. They can be very effective, but as complexity increases so does the chance that things will break or go wrong!