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TABLE 1. Stratigraphy of the White Clay Creek site.

Layer Number Height
(cm)
Thickness (cm) Plant Subfossils Radiocarbon Dating Samples Description
9 110 - 117 7 No No Modern soil and roots. No cross strata.
8 103 - 110 7 No No Fine to very fine sand layer directly below modern soil and roots. Overhangs stream bank.
7 40 - 103 63 No No Silt, light brown, finely laminated legacy sediment. No cross strata.
6 37 - 40 3 No No Silt and clay with occasional fine sand grains. Moderate brown when wet. No cross-strata.
5 33 - 37 4 No No Silt, dark yellow-brown when wet, dusky yellow when dry. No cross-strata.
4 26 - 33 7 No No Silt at base, coarsening upwards to fine sands at top. Dark yellow-brown when wet, dusky yellow when dry. Lightens in color upwards. Fine roots and occasional small stick fragments. No cross-strata.
3 19 - 26 7 Top of layer UGAMS 07518 Clay matrix with mica flecks, dusky brown when wet. Little to no plant debris, mainly fine roots with occasional leaf fragments and embedded sticks. No cross-strata.
2 7 - 19 12 Middle of layer UGAMS 07517 Clay matrix with mica flecks, dusky brown when wet. Less plant debris than layer below, and more fragmented when present. No cross-strata.
1 0 - 7 7 Bottom of layer UGAMS 07516 Pebbles and plant debris embedded in clay matrix, dusky brown when wet with mica flecks. Contains the majority of leaf subfossils. No cross-strata.

 

TABLE 2. Radiocarbon results for leaf subfossils from White Clay Creek (Table 1). * Best-fit intercept age calibrated using CALIB REV7.1.0 Radiocarbon Calibration Program (Reimer et al., 2013). The “mean probability” ages for these units are 1774, 1562, and 1778 CE, for Base, Middle and Top samples, respectively. The selected calibrated 2σ intercepts of 282, 311, and 282 yr BP (before 1950) shown above, and chosen among several possible intercept ages, represent the dates that best fit the measured 14 C ages in combination with the stratigraphic order of the samples.

Sample # Name 14 Age, Years BP, Uncalibrated
Radiocarbon Age
14C Age, Years BP, Calibrated 2σ*
(Range = CE)
UGAMS 07518 LMS Top 200 ± 20 282 +/- 14 (1654-1682)
UGAMS 07517 LMS Middle 290 ± 25 311 +/- 22 (1617-1660)
UGAMS 07516 LMS Base 200 ± 25 282 +/- 16 (1652-1683)

TABLE 3. Floristic comparison of the White Clay Creek, Big Spring Run, and Denlingers Mill sites.

  White Clay Creek
(this paper)
Big Spring Run
(Voli et al., 2009)
 Denlingers Mill
(Elliott et al., 2013)
Location White Clay Creek, Chester County, PA Big Spring Run, Lancaster County, PA W. Branch Little Conestoga Ck., Lancaster County, PA
Material Leaf and fruit macrofossils Fruit and seed macrofossils Leaf and fruit macrofossils
Age 217 to 368 BP 690 to 3,200 BP 113 to 295 BP
Herbaceous species None identified Brasenia schreberi, Carex crinita, C. stipata, C. stricta, Eleocharis spp., Najas flexilis, Polygonum spp., Scirpus spp. Present, but none identified
Woody species Acer negundo, Alnus serrulata, Fagus grandifolia, Liriodendron tulipifera, Quercus Section Lobatae, Q. Section Quercus, Salix spp. Juglans cinerea, Liriodendron tulipifera Acer rubrum, A. spicatum, Betula lenta, Castanea dentata, Fagus grandifolia, Fraxinus nigra, Quercus Section Lobatae, Q. Section Quercus, Ostrya virginiana, Platanus occidentalis, Salix spp.

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