Does bedrock turn into humus

Answer 1

No. Humus is organic matter, and formed over the years as living organisms (mostly plants) die and decompose in the soil. It is about 58% carbon, by weight.

Bedrock can decompose, too, but it never becomes humus. Depending on the type of bedrock, it breaks down into sand, silt, gravel and clay minerals. Limestone bedrock may dissolve.