Abstract
Valley confinement along upper-middle reaches of Mulloon Creek, in the upper Shoalhaven catchment of southern New South Wales, Australia, restricts floodplain development to a series of distinct pockets. These pockets comprise a downstream-thinning wedge of vertically accreted fine-grained deposits atop basal gravels. Some time before 12500 years ago a bedload-dominated river was transformed into a suspended load system. In the mid-late Holocene, swamps developed in the middle-lower part of each floodplain pocket. Within a few decades of European settlement of this region (circa AD 1820), discontinuous watercourses in some floodplain pockets had incised to form a low-sinuosity gravel-bed channel. Wedge-shaped units of post-incisional alluvium that thicken downstream overlie the swamp and floodplain deposits in the downstream part of these pockets. In the downstream-most pocket, incision commenced prior to colonization, while upstream swamps retain a continuous swamp across the valley floor. The late Quaternary evolution of this variant of discontinuous watercourse is summarized in a schematic model.
Original language | English |
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Pages (from-to) | 661-674 |
Number of pages | 14 |
Journal | Holocene |
Volume | 16 |
Issue number | 5 |
DOIs | |
Publication status | Published - Jul 2006 |