For any given sedimentary basin, the contributing rivers may drain different areas. These fluvial systems can range from the largest-scale extra-basinal rivers that are linked to bedrock catchment areas to smaller-scale basin-fringe rivers, or the smallest-scale intra-basinal streams lying entirely within a depositional basin (Galloway, 1982). Blum and Törnqvist (2000), pointed out that extra-basinal river systems act as conveyer belts, transferring AMG-47A from upland catchment areas across and into the depositional basin, whereas intra-basinal valleys simply provide local material to more distal downstream sinks forming smaller-scale depositional systems (Fig. 6). Extra-basinal systems have also been described as piedmont incised-valley systems (Boyd et al., 2006) in which a “fall line” typically marks the transition from steeper to lower gradients. Downstream of the “fall line” both deposition and transfer of sediment can occur, whereas upstream erosion dominates (Fig. 1 and Fig. 6). Piedmont-valley systems are distinguished from coastal-plain valleys, in that the latter occupy the lower depositional reaches of a S2S system (Fig. 2). This paper will primarily focus on extra-basinal, piedmont-valley systems, as the associated trunk streams contain information about the entire upstream source area, and can be used to determine the area, relief, and provenance, but we emphasize here that it is important to attempt to distinguish these valley types in ancient systems.
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