why were there no fossils found in the rocks of the pre-cambrian period in pnnsylvania?

Answer 1

While life was likely very abundant during much of the Precambrian, most were very small soft bodied organisms without bones or shells which are normally what gets preserved. Another factor is how much has happened since then. Most of the younger rocks are formed from older ones, which would destroy any fossils from the older rocks of course. Even if it isn't destroyed, it was usually buried deeply at some point in time by later sediments, and the heat and pressure turned it into metamorphic rock, again destroying any fossils even if it did get uncovered by erosion again. Most of it didn't get exposed again though, so unless we happen to get a fossil in a core sample while drilling (and recognize it as a fossil), we don't have much to go on to tell if there are fossils in the deeper layers.

Surface bedrock in Pennsylvania is mostly Paleozoic and younger sedimentary rock, except in the regions where metamorphic rock has been heavily altered before being exposed again. Any fossils from the Precambrian in Pennsylvania would be buried very deeply, probably thousands of feet down. It's not unlikely that a few are there though.

To find Precambrian fossils you need rock that was deposited in the right conditions to preserve the most delicate types of organisms, rock that was not disturbed much in well over half a billion years but is at the surface now. Like most areas, Pennsylvania just doesn't meet those conditions.

Answer 2

you must understand that fossilisation is subject to conditions.
if the rock layer was exposed more to the elements and the bones also then you can guess that fossilisation is not an exact correlation to number of species existing then.

Answer 3

very very few precambrian fossils anywhere. Because there was very very little life on the planet to become fossilizied

Answer 4

May not have been an environment with living creatures. Also, no hard shells then.