This INQUA-adapted stratigraphic approach was preferred over more traditional stratigraphic techniques (e.g., allostratigraphy) because it is designed to map high-resolution (instant – 103 years) events that may occur in a variety of depositional environments. Even though stratigraphic events have lower and upper boundaries, they are not defined by them (e.g., allostratigraphy – bounding discontinuities), Olaparib cell line a problem when identifying recent anthropogenic impact boundaries in the stratigraphic record (Autin and Holbrook, 2012). Prominent and potentially anomalous sedimentological, geochemical, or biological markers provide the

most evident means for identifying a potential event in a depositional record (Bond et al., 1993, Graf, 1990 and Graf, 1996). Stratigraphic characteristics used to identify the learn more event in this study, anomalous alluvial coal lithology, was mapped and correlated throughout southeastern Pennsylvania. The age of the coal event(s) was constrained using absolute or relative dating techniques. Radiocarbon ages and time diagnostic artifacts from previous research were used to constrain the age of coal deposits. The advancement of a stratigraphic event to an Anthropogenic Event status requires evidence of prehistoric or historic human impact that had an identifiable influence on the genesis of the event in question.

Human impact on Earth surface processes can occur through a variety of direct and indirect means, including: human-induced vegetation change, physical, chemical, and biological alteration of soil, physical removal and relocation of land, and the modification of stream channels (Goudie, 2006). Anthropogenic impacts, such as those mentioned, can lead to prominent, notable changes in the stratigraphic record of recent deposits, soils, or erosional surfaces. These effects can cause increased sedimentation, distinct changes in the physical,

chemical, or biological characteristics of sediment, or trigger erosional surfaces within a depositional environment, and thus, create a distinct stratigraphic marker. We use historical records and Ribonucleotide reductase archeological data to demonstrate how humans generated an event in the stratigraphic record. A commonly observed layer blanketing floodplains and alluvial terraces along the Lehigh and Schuylkill Rivers are coal-rich deposits, consisting of sand and silt, referred to as “coal silt” ( Nolan, 1951). Soil scientists involved in County-wide surveys have noted the presence of coal-rich alluvium. Some Natural Resources Conservation Service (NRCS) soil surveys have included the occurrence of these deposits in official soil series descriptions, e.g., Gibraltar Series (Inceptisols having an epipedon composed of coal deposits), or simply mapped them as mine wash, coal riverwash, or Udifluvents formed in stratified coal sediment ( Eckenrode, 1982, Fischer et al.