Wednesday, August 23, 2017

8/23: Percussion yields a slight improvement but sand unit proves impenetrable

View from the top of the tripod, looking down a Livingston drive-rod. These are what we push the core tube down into the sediment with. These are great for shallow to mid-depth lakes (and could be used greater depths with many rods) but we often turn to climbing rope and weight for larger lakes and ponds. 

"I am almost certain this is the top"

How to Percussion Core: 
Step 1

Step 2 
In percussion coring, you are literally wailing on the top of the core tube to drive it into the sediment. There are many different types of percussion coring setups but our more 'organic' setup worked rather well today. Large rock + core tube over shallow lake...

Using a large slab of Norwegian Wood as the top of a percussion corer (not what Lennon-McCartney were thinking)
Mike is not a crook!

Using the Livingstone corer and piston, we are able to take multiple cores out of the same hole so long as we case it with a piece of large PVC. This way we are able to take a very deep core using only 1-2.5 m core tubes each drive. To fish the second core down into the casing (above), I had to use my feet to guide it in...hence the waders.

Note how wet I've gotten after emerging from the coring 'basement.' At this point, Mike is giving it all the weight and I am in charge of the vibra-coring apparatus.
No joke, found the drive rod for the portable concrete vibrator in the pond-muck after we lost it yesterday....only took 25 min of pacing the pond and praying.

Here is a short video Maddie took while I danced across the sediment-water interface.

Western-stance with core (foreground), Havoysund (background).

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