Submitted by Anonymous on Thu, 08/09/2012 - 18:53
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High Arctic Change 2012

HI Sir

Im John Glenn from St.Marks Catholic school I was wondering whats the biggest amount of sediment you have ever seen in lakes in Maine.

Sincerly John Glenn

Sat, 08/11/2012 - 04:09

Dan Frost

Hi John and thanks for the question!Ahhh, Maine sediments are among my favorite.
Some background info: The amount of sediment that one can find in lakes in Maine varies greatly based on a number of factors: the sedimentation rate, what are the stream inputs, how much photosynthesis happens in the water, and what is the underlying sediment from before the water body was actually a lake. If you've ever put your feet down in a 'mucky' lake bottom in Maine you know it is full of organic matter (algae remains, plant tissue) plus some sand (inorganic) mixed in. Near the shorelines you'll typically find thicker sediment layers with more vegetation and sand/silt blown in from the watershed. In the middle of the lake the sediment is typically thinner (because you need to transport material further from the shores) and composed of finer sand/silt with the vegetation primarily coming from algae settling to the bottom.
How thick is it? Well, we typically look at the sediments from the middle, deepest parts of lakes. The thickest I've ever cored consisted of about 20 ft. of lake sediments before running into glacial sediments that were deposited just after the Laurentide Ice Sheet retreated from the Maine landscape. That's 20 ft. of sediment piling up very, very slowly for about 13,500 years at a rate of only about 0.2 to 1.5 millimeters per year (depending on those factors I mentioned earlier). To core something that thick is a bit of a process when it is over 100 ft. deep in the lakes you're working on but a lot of fun! It is especially fun to open your cores and be able to point at part of it maybe 15 ft down and say, "Wow, that was laid down 7,200 years go!"
Thanks again for the question and let me know if I can answer any more!
-Dan