Last updated on December 11th, 2025 at 07:24 am
Science estimates that the Earth is 4.6 billion years old. The Fleurieu has some on the oldest rock formations which date back to the Precambrian super interval of time which represents 88% of Earth’s time scale. The geology from this time includes the Paleoproterozoic period in the Proterozoic eon.
The eon is the broadest category of geological time. Earth’s history is characterized by four eons; in order from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. Collectively, the Hadean, Archean, and Proterozoic are sometimes informally referred to as the “Precambrian.” (The Cambrian period defines the beginning of the Phanerozoic eon; so, all rocks older than the Cambrian are Precambrian in age.) (Digital Atlas of Ancient Life | Geologic time scale).
The table below lists the representative time represented in rock and material composition in the Fleurieu.
| Geological epochs | Millions of years | Periods | Era | Eon |
| Holocene | 0.01 to present | Quaternary | Cenozoic | Phanerozoic |
| Pleistocene to Holocene | 2.6-0.01 | Quaternary | Cenozoic | Phanerozoic |
| 7 epochs | 66 to 0.01 | Paleogene to Quaternary | Cenozoic | Phanerozoic |
| Late Carboniferous to Early Permian | 329 to 275 | Carboniferous and Permian | Paleozoic | Phanerozoic |
| Early Cambrian | 541 to 522 | Cambrian | Paleozoic | Phanerozoic |
| Neoproterozoic III to Ediacaran | 635 to 541 | Neoproterozoic | N/A | Proterozoic (Precambrian) |
| Cryogenian to Ediacaran | 720 to 538 | Neoproterozoic | N/A | Proterozoic (Precambrian) |
| Cryogenian | 720 to 635 | Neoproterozoic | N/A | Proterozoic (Precambrian) |
| 7 epochs | 2500 to 1600 | Paleoproterozoic to Mesoproterozoic | N/A | Proterozoic (Precambrian) |
The Department for Energy and Mining of the Government of South Australia provides a detailed geologic time scale which can be used to unlock the terminology as well as the plants and animals which existed as a result of conditions of the earth in the ancient past.
Video: A Brief History of Geologic Time
This 13 minute video produced by PBS on its YouTube channel provides an overview of geologic time.
Digital Atlas of Austalia Lithology Layers
The Digital Atlas of Australia contains a number of lithology (rock type) layers which allow the identification of a rock and material deposits across Australia. Across the Fleurieu, there is a vast variety of rock formations which stretch back in geological time.
Rock formations across the Fleurieu
The table below is a list of the rock and sand formations which occur across the Fleurieu, the geological epochs, and approximate location on the Fleurieu.
| Fleurieu lithology | Geological epochs | Locations |
| alluvium 38485 | Holocene | Myponga flat plain; Inman Valley river and tributaries; Hindmarsh Tiers road |
| Semaphore Sand Member | Holocene | Part of the Newland Head Conservation Park to the west of Victor Harbor |
| colluvium 38491 | Quaternary | borders the intersection of Nangkita and Tookayerta creeks and lies south of Mount Observation |
| coastal dunes 38488 | Quaternary | Occupies most of the New Headland conservation park |
| sand plain 38499 | Cenozoic | The flat valley which extends across Seaford, McLaren Vale, Aldinga, and Willunga |
| sedimentary rocks 72357 | Cenozoic | Runs along Range road near Delamere at the bottom of the Fleurieu; at the tip of the Fleurieu at Cape Jervis; and at an area near Myponga Conservation Park |
| Cape Jervis formation | Late Carboniferous to Early Permian | There are three main distributions of this formation: Inman Valley uplands which stretch from Myponga, Inman Valley heading towards Victor Harbor, and the uplands of Second Valley. A fourth distribution is at coastal Hallett Cove. |
| Normanville Group | Early Cambrian | Runs along the coastal area from Carrickalinga, Myponga Beach forming the uplands south of Sellicks Beach. |
| Keynes Subgroup | Early Cambrian | Runs along the coast at the foot of Cape Jervis; Runs between Mount Magnificent and Ashbourne. |
| Bollaparudda Subgroup | Early Cambrian | Runs along the Deep Creek coast towards Victor Harbor. |
| Encounter Bay Granite | Cambrian | Igneous granite intrusions which appear as islands of the coast at Victor Harbor. |
| Umberatana Group | Cryogenian to Ediacaran | Runs from Second Valley towards Cape Jervis near Delamere; Another distribution occurs as uplands between Hallett Cove, Adelaide Plains and Aberfoyle Park. |
| Burra Group | Cryogenian | Runs north from Myponga along the ridge reaching Echunga and parts north as well as encompassing the area around and north of Clarendon |
| Wilpena Group | Neoproterozoic III to Ediacaran | Runs north west as part of the uplands above the flatlands which make up Sellicks Beach and Willunga. |
| Barossa Complex | Paleoproterozoic to Mesoproterozoic | Reaches north above Mount Compass, Yundi, and stretches across Kyeema Conservation Park. |
References
- Australian Government 2025, Digital Atlas of Australia, viewed on 4 December, 2025, <https://digital.atlas.gov.au>. This is the official website of the Digital Atlas of Australia, a mapping tool for overlaying information from Australian Government datasets.
- Government of South Australia 2025, Geologic Time Scale, viewed on 28 November, 2025, <https://sarigbasis.pir.sa.gov.au/WebtopEw/ws/plans/sarig1/image/DDD/203866-001>. This 1 page PDF provides a time scale for the geologic time scale which maps eras, periods, and epochs against millions of years and significant evolutionary activity in the plant and animal kingdoms.
- PBS Eons 2017, A Brief History of Geologic Time, viewed on 28 November, 2025, <https://youtu.be/rWp5ZpJAIAE?si=ZP3vcTTvK78IIym2>. This 13 minute video provides an overview of geologic time. This is the best quick review of geologic time.