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Figure 55. Soilstone crust accumulates as wafer-thin layers. In Florida, normal crust color is white or off-white, like the bottom layers in this specimen. The dark brown and red colors are caused by iron and other non-native minerals derived from airborne African dust that periodically blankets the Florida-Caribbean region (Fig. 5; Muhs et al., 1990; Shinn, 1997; Prospero, 1999; Shinn et al., 2000; Griffin et al., 2001). A dental drill is used to cut individual layers from a crust sample. The crust is sampled every few layers from top to bottom for radiocarbon dating.

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Coastal & Marine Geology Program > Center for Coastal & Watershed Studies > Professional Paper 1751