Taconite Inlet Project


8. Changes in the oxicline

Stratigraphic correlation of the cores from the transect in Lake C2 revealed that the oxicline has deepend by approximately 5m since 3300 BP. Varves in the shallower cores were diffuse and difficult to resolve, possibly indicative of bioturbation. In contrast, varves from the deeper cores were consistently well-defined.

The observed pattern of well-defined and diffuse varves are evidence for the deepening of the oxicline and the epilimnion in Lake C2. Most of the deepening of the aerobic zone appears to have occurred in a relatively short period of time after 1250 BP.


Schematic depth-time relationship between diffuse (aerobic) and well-defined (anaerobic) varve sedimentation. Red core sections indicate diffuse varve deposition.

Long-core varve record index page

Lake sediments index page