2-4 Cape Bridgewater karst area

This information has been developed from the publications:

An assessment of the Geological/Geomorphological Significance of Private Land in the Shire of Portland (1981) by N. Rosengren, J Mallen, T Shepherd.

Geological heritage sites, including sites of geomorphological interest and volcanic heritage sites, are under regular revision by the Geological Society of Australia, especially in the assessment of significance and values. Reference should be made to the most recent reports. See the Earth Science Heritage section of the Geological Society of Australia website (external link) for details of geological heritage reports, and a bibliography.

Locality:	7121-337520. Six kilometres south-west of Bridgewater.
Access:	Bridgewater Road, Blowholes Road, J. Amost road, Amost Road.
Geology/Geomorphology:	Basalt from the Cape Bridgewater volcano forms a coastal plateau bounded by high cliffs. The basalt is overlain by calcareous and siliceous sand ridges. The calcareous materials contain numerous infilled solution pipes now exposed as columnar structures known locally as "Petrified Forest". A typical karst landscape of disorganised drainage and closed depressions has developed.
	Tufa terraces occur on the coast above the basalt where calcite enriched groundwater emerges from the dune limestones. Sea caves have been eroded in the basalt of the cliff face.
Significance:	State. The areas has a number of rare limestone and coastal features including the infilled solution pipes, sea caves and tufa terraces.
Management:	Reduction of water movement onto the coastal cliffs would lead to the drying up and decay of the tufa terraces. Activities which will deplete the underground water supply should be prohibited.
Reference:	Boutakoff, N. (1963). The Geology and Geomorphology of the Portland Area. Geological Survey of Victoria, Memoir No. 22. Matthews (1979)

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