Let's see
Find a fossil, so let's build a whole culture around it.
To quote from the New American Encyclopedia:
"Index fossils are useful in identifying and dating rock strata."
"The age of fossils - including index fossils - is usually determined from the age of the rock in which it is found."
So the rock strata is dated by the index fossils contained therein, and then the age of index fossils is determined by the age of the rock strata in which it is found. How convenient.
As far as the Strelley Pool Formation goes, "Palaeontologists and geologists conclude that this area was once submerged under the ocean and formed a fairly flat area, perhaps the floor of a shallow ocean. As this now-arid region was once underwater, stromatolite-forming microbes would have thrived in a shallow sea where the water kept them moist but the Sun???s rays could still penetrate and fuel photosynthesis."
Fossils are most common in sedimentary rock formations - river beds, ocean floors, flood zones, watering holes - places that were underwater at some time. Many of those underwater places are now on dry land, such as the Strelley Pool.
