1-6 Lower Glenelg

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:	7121-234870 to 003890. 7122-040940 to 000948. This is an extensive area adjacent to the Glenelg River from the junction of the Moleside Creek to the mouth of the Glenelg River.
Access:	Roads off the Portland-Nelson Road, e.g. River road, Sapling Creek Road, Bully Ranges Road, Wanwin Road.
Ownership:	Mainly Crown Land (Lower Glenelg National Park) and some private land. The karst area needs to be managed as a single large unit which is independent of land boundaries.
Geology/Geomorphology:	The caves are predominantly joint enlarged systems in the Tertiary limestones of the Heytesbury Group. Joint enlargement is due to both phreatic and vadose water. The area includes good example of collapse dolines, sinkholes, caves (including a tourist cave G-6), blind gullies and springs. Thirty-two caves and features have been numbered by the Victorian Speleological Association. Numbered caves on private land include G-11D (a collapse doline), G-12 (a 50 metre cave sloping to deep water), G-13 (a cave 70 metres long and 10 metres deep containing bones).
Significance:	State. This is one of the largest karst areas in Victoria. It contains several caves and a wide variety of other karst features.
Management:	The entire karst area must be considered as a unified management unit and the principles outlined on the "Management of Karst Areas" should be referred to. Particular emphasis is placed on the need to control rubbish dumping and thus to avoid ground water pollution or the destruction of particular sites, e.g. G-11D. Pollution of ground water on private land may affect the water quality of the Lower Glenelg River. The Shire should therefore provide more small rubbish tips at suitable sites throughout the area. Rubbish in caves and sinkholes should be cleared out and dumped in the new refuse sits.
	Changes in land use over the karst area need to be considered in terms of their possible adverse effects on the supply and quality of underground water. In particular, the impact of extending the softwood plantation area and increasing the number of building sites needs to be investigated more completely. Land clearing may lead to siltation of underground drainage lines. This can adversely affect the cave environment - for example by lowering the humidity of the cave or reducing the rate of stream outflow. Caves G-6 and G-14 are particularly susceptible to these changes.
	Quarrying of sites should only be permitted where no deterioration of major karst features would occur.

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