Why is so little known about the Precambrian time?

Question

Geological Time Scale Mural

Answer 1

Pre-Cambrian life was mostly soft-bodied -- there were very few if any creatures with bones, skeletons, or hard shells, so there were very few fossils left.

Besides, it was a long, long time ago -- and geological activity on the earth (volcanic action, subduction of continental plates, erosion, etc.) have wiped out a lof of what was the surface of the earth then. :)

Answer 2

The Precambrian Time

Answer 3

most of the info we know about previous geologic time periods comes from sedimentary rock, which is formed when layers of sediment build up on top of each other. older layers appear at the bottom, while younger layers appear on top. however, this rock doesn't always stay there: the very bottom of the earth's crust gets so hot that it actually melts off, so we don't have info about the very oldest time periods (like the precambrian). also, plate tectonics comes into play: sometimes, one continental plate pushes another one down into the molten magma of the earth's interior, which destroys the continent's rock.