The uneven transition zone from the outer core to the mantle is known as the discontinuity.

The transition zone between the crust and mantle is called as MOHOROVICIC discontinuity

the precambrian aged rocks could be found in australia. australia is a region that has a lot of ancient civilization history from million years ago. in this region, there are a lot of recognizable fossils buried in its land which is considered a precambrian-aged rocks