Lynn Volcanic Complex

The Lynn Volcanic Complex is a suite of Proterozoic felsic volcanic rocks, situated in a block north of the Boston Basin. It includes rhyolite, rhyodacite, welded ash flows, tuff and some andesite and basalt. Unlike the neighboring Mattapan [Volcanic Complex], the Lynn complex lacks volcanic breccia and has a greater variety of texture and composition in its rhyolitic rocks.
It lies unconformably on top of the Dedham Granite. A mass of Dedham Granite at Pine Hill in Medford, Massachusetts contains inclusions of the Lynn complex.