Which layer of soil has little or no humus

O Horizon - The top layer of soil made up mostly of leaf litter and humus.

There are 6 layers of soil - O horizon, A horizon, E horizon, B horizon, C horizon, R horizon. Humus is an organic material mostly composed of decomposed living material like of animals, leaves or etc. which turns as raw or natural nutrients. This humus or this organic material is less or almost not found in the C horizon layer of the soil. Moreover, It is made up of torn and shredded bedrock that forms its layer next to the last soil, R horizon.