Question

Why would you likely not find any fossils in the bedrock if you were hiking up Mt. Marcy in the Adirondack Mountains?

Answer 1

most likely because the bedrock is igneous.

Explanation:

i don't know the Adirondack mountains nor do I know Mt Marcy, so forgive me if i am incorrect.
but the most likely reason why you wouldn't find fossils in rocks is because the rocks are igneous in nature, rather than sedimentary or metamorphic (both of which could contain fossils).
As igneous rocks are formed from molten rock (magma) that has cooled, the likelihood of plants/animals being present is very slim and even if there were any living organisms present any plant/animal remains would be destroyed by the high temperatures of the liquid rock. So no fossils are ever found in igneous rocks.