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FIGURE 1. Location of the White Clay Creek leaf mat site, Chester County, Pennsylvania.

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FIGURE 2. White Clay Creek leaf mat site, illustrating the contact (at trowel) between the darker hydric soil layer containing subfossil leaves and the overlying, lighter-colored legacy sediments. Stadia rod for scale.

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FIGURE 3. Alnus serrulata (Hazel Alder), EMS 425002. 1, Whole specimen; 2, Peltate scale and simple trichomes; 3, Stipitate gland trichome; 4, Detail of teeth; 5, Trichomes at vein junction; 6, Areolation with simple and branching freely ending veinlets.

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FIGURE 4. Fagus grandifolia (American Beech). 1, Leaf fragment, showing regularly spaced secondary veins, EMS 425004; 2, Detail of venation on EMS 425004; 3, Trichomes at vein junction, EMS 425004; 4, Trichomes at the vein junction of a modern F. grandifolia leaf from York County, Pennsylvania (collection Y1.2 of Wilf, 1997); 5, Rounded tooth on subfossil, EMS 425005; 6, Tooth and rounded sinus on modern F. grandifolia leaf from York County, Pennsylvania (collection Y1.2 of Wilf, 1997); 7, Trichome, EMS 425004.

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FIGURE 5. Quercus Section Lobatae (Red Oak group). 1, Leaf fragment showing asymmetrical lobe with acute apex, EMS 425011; 2, Abaxial leaf surface of EMS 425011, with randomly oriented stomata; 3, Simple trichome on leaf surface near secondary vein, EMS 425011. 4, Trichomes along a tertiary vein, EMS 425011; 5, Individual stoma of modern Q. rubra from York County, Pennsylvania (collection Y2.3 of Wilf, 1997) showing T-shape junction; 6, Individual stoma of EMS 425011.

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FIGURE 6. Quercus Section Quercus (White Oak group). 1, Lobe of modern Q. alba from York County Pennsylvania (collection of Wilf, 1997); 2, Subfossil, EMS 425008, showing entire margin with fimbrial vein and retuse, asymmetrical apex.

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FIGURE 7. Liriodendron tulipifera (Tulip Tree). 1, Subfossil samara, EMS 425015; 2, Thickened ridge at basal attachment site of EMS 425015; 3, Mucronate samara tip from EMS 425014.

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FIGURE 8. Three Salix spp. (Willow) subfossils. 1, EMS 425022; 2, EMS 425021; 3, EMS 425023; 4, Salicoid tooth, EMS 425021.

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FIGURE 9. Acer negundo (Box Elder). 1, Leaflet, showing shallow lobes and rounded sinuses, EMS 425016; 2, Trichomes along veins, EMS 425016; 3, Trichomes along tooth margin, EMS 425016, with increased density on basal side of tooth; 4, Tooth of modern A. negundo from York County, Pennsylvania (collection Y2.2 of Wilf, 1997), showing the same general trichome pattern.

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