Paleo And Environmental Magnetic Investigations In The Appalachians Of Pennsylvania PDF Download

Paleosecular variation, mineral magnetic, magnetic fabric and $\sp{14}$C studies were carried out in three lakes in Pennsylvania. In Lake Waynewood, a clear record of watershed changes over the past 3700 years BP is available. Prior to 2700 BP, little evidence of allogenic influx is present, whereas, at 2700 yrs BP, the magnetic mineralogy and the magnetic fabric suggest allogenic sources for the magnetic minerals. Between 2700 and 1900 yrs BP, major changes in mineral magnetic properties suggest an interval of instability in the watershed. Conditions were more stable between 1900 and 100 yrs BP, and at 100 yrs BP, the effects of clearcutting are apparent. Similar studies were carried out in Lakes Lacawac and Giles. In all three lakes, a sharp change in mineral magnetic properties, most notably a drop in the ferrimagnetic content of the sediments, is seen $\sim$1800-1900 yrs BP. The change in mineral magnetic properties is consistent with increased input of antiferromagnetic minerals (goethite or hematite), implying that all three lakes were responding to a regional or global climate event causing increased erosion.