The lava layers in this remnant indicate that the deposition took place in at least 2 major phases of volcanic activity in the Late Miocene, about 6-7 Ma.
Fossils are generally found in sedimentary rock not igneous rock.
Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.
It is considered to be dormant, rather than extinct, so there is the potential for another eruption.
Volcanic fields in Australia It is thought that eastern Australia has been passing over a hotspot as it drifted north, leading to a chain of volcanic activity from north to south.
Australia has some of the oldest geological features in the world with the oldest known rocks dating from more than 3000 million years ago and rare zircon crystals dating back 4400 million years located in much younger rocks.
The zircons evolved very soon after the planet was formed.
This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Some do not change with time and form stable isotopes (i.e.
those that form during chemical reactions without breaking down).
Some areas of Victoria and Queensland are geologically much younger as a result of volcanic activity which last erupted a few thousand years ago.
Australia's youngest mainland volcano is Mount Gambier in South Australia which last erupted only about 6000 years ago.
Basaltic lava flows are prominent along the Eastern Uplands, as well as some of the offshore islands.