| Rock magnetism is a versatile methodology applicable to a wide range of paleoenvironmental studies. The magnetic record of loess deposits may be one of the most detailed and useful records of Quaternary climate change on the continents. Stratigraphic variations of magnetic parameters define alternating zones of high and low concentrations of magnetic minerals. All the concentration-sensitive magnetic parameters, including susceptibility, ARM, and SIRM, show an increase within the interstadial Gilman Canyon Formation and a systematic decrease within the Wisconsinan Peoria loess. Magnetic parameters show a dramatic increase at about 13 ka. Long-term variations of magnetic concentration also synchronize with hemispheric environmental changes, including {dollar}deltasp{lcub}18{rcub}{dollar}O and dust content variations within the Greenland icecore. The higher resolution data produced in this research allowed identification of short term climate fluctuations such as multiple pedogeneses during the Last Interstadial and possible Younger Dryas.; Grain size characteristics of magnetic minerals also vary with the stratigraphic units. Soils with higher concentrations also exhibit a distinctively finer granulometric composition, whereas unweathered loesses with lower concentrations contain coarser grains.; The influence of climate change on magnetic records is confirmed by a high correlation between the rock magnetic parameters and biological proxies such as stable isotopes and opal phytoliths. Rock magnetic data appear to be better correlated with temperature-sensitive biological proxies than does a precipitation-sensitive index such as the aridity index derived from opal phytoliths. Simultaneous, higher resolution sampling of magnetic and biological proxies from the 14LV1071 (DB) site proved to be a better sampling tactic, and enhanced the feasibility of rock magnetic parameters as independent climate proxies. |
