[[Image:Mystic Lakes, Massachusetts (map).jpg|thumb|right|250px|The Upper and Lower Mystic Lakes.]]
The '''Mystic Lakes''', consisting of the '''Upper Mystic Lake''' and the '''Lower Mystic Lake''', are closely-linked bodies of water in the northwestern suburbs of [[Boston]], [[Massachusetts]].
The lakes lie at an elevation of 1 meter above sea level, within the towns of [[Winchester, Massachusetts|Winchester]], [[Arlington, Massachusetts|Arlington]], and [[Medford, Massachusetts]]. The Upper Mystic lake is fed by the [[Aberjona River]], and drains south into the Lower Mystic Lake, which in turn empties into the [[Mystic River]] and thence [[Boston Harbor]].
Lower Mystic Lake is a [[meromictic|meromictic lake]], which means that the lake has a deep layer of water that rarely, if ever, mixes with its top waters. As a consequence, the sediments at the bottom of Lower Mystic Lake haveaccumulate beenin accumulatingannual layers (or [[varves]]) that have been nearly undisturbed for a thousand years. Such varves in meromictic lakes preserve an historical record something like tree rings do. In the case of Lower Mystic Lake, the varves have been used by Mark Besonen and his collaborators to study the historical incidence of hurricanes.<ref>Anonymous (2005). [http://umassmag.com/Fall_2005/Mysteries_in_the_Muck_967.html "Mysteries in the MuchMuck"], ''UMass Magazine Online'', Fall 2005 issue. Online version retrieved May 1, 2008.</ref><ref>Besonen, Mark R., Abbott, Mark B., Francus, Pierre and Bradley, Raymond S. (2006). "A 1,000-Year High-Resolution Hurricane Activity Record for the Boston Area", Gulf Coast Association of Geological Societies 2006 Convention, September 25 - 27, 2006, Lafayette, Louisiana.</ref><ref>Besonen, Mark R. (2006). [http://proquest.umi.com/pqdlink?did=1221680571&Fmt=7&clientI%20d=79356&RQT=309&VName=PQD ''A 1,000 year high-resolution hurricane history for the Boston area based on the varved sedimentary record from the Lower Mystic Lake (Medford/Arlington, Massachusetts)''], [[University of Massachusetts Amherst]] doctoral dissertation.</ref>
Although the Mystic Lakes are popular for swimming, sailing, and fishing, the Upper Mystic Lake suffers from contamination by [[arsenic]] and other heavy metals from the [[Aberjona River]].<ref>
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