49. Jacks Beach - Silurian and Tertiary Outcrops

This information has been developed from one or more of these publications:

Sites of Geological and Geomorphological Significance in the Westernport Bay Catchment (1984) by Neville Rosengren.
Sites of Geological and Geomorphological Significance in the Western Region of Melbourne (1986) by Neville Rosengren
Sites of Geological and Geomorphological Significance on the Coast of Port Phillip Bay (1988) by Neville Rosengren.
Sites of Environmental Significance in the Flood Plain of the Upper Yarra Valley Region (1983) by Neville Rosengren, Douglas Frood and Kim Lowe (as part of a study of Sites of Environmental Significance by the University of Melbourne for the then Upper Yarra Valley and Dandenong Ranges Authority).

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.

Location:	Tyabb – 425572 to 442535. The site includes the coastal wetlands and tidal flats south from Reid Parade to the south of the Crib Point jetty.	Folded Silurian strata, Woolleys Beach, Site 49
Access:	Reid Parade, Woolleys Road, and The Esplanade.
Ownership:	Crown Land and some private land.
Geology/Geomorphology: Folded Silurian Strata, Site 49	Silurian sedimentary rocks underly the area and are well displayed at Golden Point immediately north of Woolleys Beach. This outcrop includes steeply dipping and folded beds which are the most extensive outcrop of Silurian strata on the entire mainland shoreline of Westernport Bay. Smaller outcrops are at Jacks Beach and on the small un-named point one kilometre to the north-west. Well bedded and cross-bedded ferruginous rocks and grits of the Tertiary Baxter Formation are well displayed to the north and south of the Crib Point jetty.
	The influence of the hard rock outcrops on coastal morphology is apparent in the cusp-shaped headlands north-west of Woolleys Beach. Salt marsh peats and muds and mangrove muds have largely infilled the estuary of the Warenquite Creek and in part mantle the Silurian outcrops. The inner margin of the coastal deposits is a low bluff that is best defined between Woolleys Beach and Jacks Beach. Sand and gravel derived from the break-up of the Baxter formation have formed beaches adjacent to the Crib point jetty and these are augmented by shell fragments from the extensive shell banks that lie on the inter-tidal mudflats north of the jetty.
Significance:	State. The Silurian outcrops are the most extensive of this strata on the mainland shore of Westernport Bay. There is also a major display of the Tertiary strata (Baxter Formation) and both are readily accessible as reference sites for these materials. The bank of tidal overwash shells and shell sands that extends north from the Crib Point Jetty is easily accessible at low tide as the substrate is quite firm. This provides a rare opportunity to examine this material and its depositional structures without the need for boat transport.
Management:	Class 1. Any extension to coastal facilities must be planned to avoid obscuring the Silurian and Tertiary outcrops or disturbing the shell banks north of the jetty. Dumping of dredged material in the area and land reclamation schemes should be prohibited.

Image: Sites of Significance Westernport Bay

Tidal overwash shell banks north of Crib Point Jetty, Site 49

Site 49, extends south from Reid Parade to Crib Point. This site includes intertidal areas north of the Crib Point Jetty

Page top