Geoheritage values of Beenyup Swamp, in the Yellagonga Regional Park, Western Australia

Unno, Joy1

1V & C Semeniuk Research Group

Beenyup Swamp in the southern part of Yellagonga Regional Park on the Swan Coastal Plain in Western Australia is a Holocene wetland with geoheritage values.  It is part of the chain of linear wetlands belonging to the Yanchep Wetland Suite that is located between limestone ridges of the Spearwood Dunes near the boundary of the quartz-sand-dominated Bassendean Dunes.  Instead of being dominated by calcilutite as are other wetlands in this Suite, Beenyup Swamp is a basin stratigraphically dominated by peat. As such, in contrast to other basins in the Yanchep Wetland Suite that are mostly calcilutite-filled, Beenyup Swamp has a stratigraphy of thick homogeneous peat, with stratigraphic evidence of fire scarring including buried lumps of charcoal, and ubiquitous diagenetic products of acidic groundwater.  The sequence of peat in this region of the Yanchep Wetland Suite dates back to 8000 years BP and contains a diagenetic record of plant organic matter grading from fibrous peat to organic gel.  The stratigraphy, the Holocene fire history, the acidic water diagenesis providing a model of peat accumulation and peat diagenesis at Beenyup Swamp is a geological ensemble of geoheritage significance.


Joyleen Unno (MSc) is a wetland scientist with over 20 years of experience studying coastal and inland wetlands (mangroves, inter-tidal flats and estuaries, and inland basins) in Australia in conjunction with the V & C Semeniuk Research Group in Perth, Western Australia; In recent years, Joyleen has become involved in the geoheritage aspect of wetlands, whereby wetlands may be conserved for their significant on-going geological processes and their stratigraphic value to scientific knowledge. Joyleen also is a founding Committee Member of the Wetlands Research Association Inc.

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