Rottnest Island — a geology guide

Did you know that as well as sun, sand, and surf, the little rocky island of Rottnest has some geological features of international significance? The Geological Survey of Western Australia (GSWA) has published a pamphlet on some of the world-class geology found on Rottnest. Using the pamphlet, you can visit nine geological sites round the island from West End (in the far west) to The Basin (just round the corner from Thomson Bay).
Parker Point, Rottnest
Parker Point
Cauliflower Coral, brain coral
Cauliflower Coral, brain coral.

Rottnest Island tells the story of sea-level changes over the last 140 000 years — when the sea was both higher and lower. Author Bob Gozzard draws attention to shoreline platforms and notches that are +2.4, +1.1, and +0.5 metres above present-day sea level. These platforms and notches were formed when the sea stayed at the same level for long enough to allow erosion to cut a platform, a notch, and an overhanging visor — before shifting higher or lower and restarting the same process at a different level.

At Fairbridge Bluff ancient corals grew about 125 000 years ago — and there is a similar modern coral reef growing today offshore from Parker Point. A snorkel, mask, and fins will give you a great view underwater of about 25 species of coral.

‘Paddy-field’ terraces (so named as they look like paddy fields!) and algal polygons are beautifully developed at Wilson Bay. The algal polygons are irregular hexagons and pentagons outlined by the growth of brown seaweed, probably due to the grazing habits of herbivorous reef fish, which seem to be responsible for the creation and maintenance of the polygon boundaries.

How to access the pamphlet

The free full-colour pamphlet is available from Mineral House, from the Rottnest Visitor Centre, and from other local Visitor Centres catering to the Rottnest visitor. It can also be downloaded free from the DMP eBookshop.

New App: Rottnest Island geology in your pocket

The Geological Survey of Western Australia (GSWA) has teamed up with Everythere to create a Beta version of a new app to explore Rottnest Island using your smart device. As you walk near key location points around the island, you’ll get notifications about the geology and formations of each spot. Each location gives you geological information written by geologists from GSWA.

To start exploring Rottnest, just follow these steps:

Download Everythere from iTunes App Store.

  1. Open app, click on the Tours tab and swipe left on the Rottnest Island – A Geology Guide banner. Tap on Download to pre-download all media.
  2. Start the interactive tour by tapping on the Rottnest Island – A Geology Guide banner followed by the Explore button.
  3. Begin walking or cycling around the island. As you pass each location coordinate, the digital media will activate on your device.

For Android phones.

  1. In the Google PlayStore search for ‘Apps ppl’
  2. Download the ‘Everythere’app
  3. Open the app and search the tours
  4. Tap on the hexagon on ‘Rottnest Island — a geology guide’  to download all the media ready for your visit
  5. Tap on the photo to start the interactive tour (Introduction, Setting off, Explore)
  6. Begin walking or cycling around the island. As you pass each of the location coordinates, the digital media will activate.

Please note that the locations will not be visible until you are on the island and within range.

So grab your bicycle, snorkel, fins and phone and head over to Rottnest for some fun lessons in geology.

As this is a Beta version only, we would love to hear your feedback over the next few months.

Contact
For further information and to provide feedback on the app contact:
geotourism@dmirs.wa.gov.au