Lake George is in a rugged, densely wooded area in the eastern Adirondack Mountains of New York. Relict glacial sediment and modern sediment rich in organic matter floor the lake. The relict sediment includes Pleistocene varved lake clay containing iron-manganese nodules. Beneath a cover of modern organic-rich silty clay much of the lake is underlain by varved clay.
A comparison of lake bottom morphology with both clay and organic matter content and sediment color shows that an interrelation exists between these variables. Sediment in the deeper parts of the lake is black, and clay and organic matter contents are generally high. In the shallower part of the lake sediment is brown in color, usually sandy, and low in organic matter. Tree bark, spore capsules, leaves, and needles compose much of the identifiable organic matter in the sandy near-shore bottom sediments. The organic material which enters the lake primarily in the fall is derived from vegetation in the drainage basin. The fabric of organic matter in the deeper parts of the lake cannot be identified because of advanced decomposition. The organic matter content of the bottom sediments of the southern basin of Lake George generally exceeds that of the northern basin, because pollution from permanent settlements along the shores of the southern basin accelerates accumulation of organic matter by enhancing phytoplankton productivity in the southern basin.