Living with cliffs - AngleseaCase studies from Victoria’s south-west coast

Coastal Management Fact Sheet

These case studies demonstrate some of the diversity of our spectacular rocky coast, and show how coastal cliff hazards have been understood and managed to reduce risk to the public

Victoria’s geological heritage

The rocks that form the coastal cliffs of Victoria vary greatly in size, geology, age and stability. Understanding how they have developed and changed enables us to appropriately manage these iconic landscapes. This ensures they are protected and can be safely enjoyed for years to come.

Demons Bluff

The sheer cliffs of Demons Bluff (pictured right) are a prominent coastal feature of Anglesea, in the south-west of Victoria. Rising from the mouth of the Anglesea river up to a maximum height of 50 m near Grinders Point, they then fall again to a height of 10 m near Black Rock.

These cliffs are composed of layers of soft siltstones and sandstones, deposited up to 45 million years ago then uplifted and slowly eroded landward. The beach below is submerged at high tide and the Surf Coast Walk extends along the cliff tops.

Due to the softness of the rock, these cliffs are easily eroded, and have experienced a number of slips and collapses, small and large. Between Grinders Point and Black Rock lies the 2 km long Demons Bluff Landslide Complex. This feature is made up of a number of segments that have progressively slipped seaward.

While currently stable and vegetated, further collapse of this feature cannot be ruled out. Therefore public access to this area is restricted, with the Surf Coast Walk passing inland and above the landslide complex. The Eumeralla Scout Camp is set back a safe distance from the landward edge of the slip.

While currently stable and vegetated, further collapse of this feature cannot be ruled out. Therefore public access to this area is restricted, with the Surf Coast Walk passing inland and above the landslide complex. The Eumeralla Scout Camp is set back a safe distance from the landward edge of the slip.

Southside

Continuing east, between Point Addis and Southside-Bells Beach, vertical cliffs ascend again as part of the the Jarosite Headland. The same siltstones at Demons Bluff are again exposed as dark silty clays beneath paler sediments.

Near the top of this cliff bed contains the mineral jarosite that was mined in the 1920s to produce red oxide pigment, use to paint the carriages of Melbourne’s historic trams, the ‘red rattlers’.

Living with cliffs

As with Demons Bluff, the Southside cliffs are also easily eroded and have experienced a number of slips (pictured above).

Melba Parade

Adjoining the township of Anglesea the cliffs between the Point Roadknight and the Anglesea River are also undergoing natural retreat. Failures in these areas have ranged from minor cliff falls to larger-scale falls, such as the Melba Parade landslide in 1973. This slip occurred at the end of seventh avenue down to the beach at Soapy Rocks (pictured below).

Intervention measures introduced as a result of this landslip included reprofiling the slumped mass, construction of drains to control surface run-off and installation of a timber pilled retaining wall.

Risk management on cliffs

Coastal managers are encouraged to consider risk mitigation strategies that are proportionate to the type and intensity of use, protecting public safety where required while maintaining the natural character of the coastline.

These three case studies demonstrate the different risk management approaches for a high-use town centre coastline and more remote access area. A cliff collapse at Melba Parade would likely cause more damage to life or infrastructure than at Demons Bluff or Southside. Therefore at Melba Parade a combination of risk mitigation strategies, including geotechnical assessments are required. For the other locations, ongoing monitoring is required due to the high recreational use by the public. Warning signs and fencing are erected to discourage access to the cliff edge provide sufficient risk mitigation at Demons Bluff and Southside unless conditions or there are changes in the profile. All sites have restrictions on access at time of higher tide and warning signs are erected.

Ongoing monitoring and review of coastal risks helps ensure timely implementation of any new mitigation actions where required, so that the public can continue to safely enjoy these spectacular rocky landscapes.

Published by the Victorian Government Department of Environment and Primary Industries Melbourne, September 2013

© The State of Victoria Department of Environment and Primary Industries Melbourne September 2013

This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.

References: Bird, E.C.F., 1993. The Coast of Victoria. Melbourne University Press, Melbourne 324 pp.

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What can I do to help?

Avoid walking near cliff edges or at the base of cliffs and encourage others to do the same

Keep to formalised paths at the cliff topDo not climb on cliffs as this can cause localised

damage and increase the rate of erosionAvoid damaging vegetation: vegetation promotes water

infiltration and reduces erosive runoff Obey all signs and stay behind safety fencesIf you see evidence of a recent slip or collapse, take a

photo and report it to your local land manager.