There are two very clear examples in this stratigraphic section. They are two burrow holes created by fairly small animals originating in the humus layer and intruding into the shelly layer beneath.

Humus, the top layer of soil, is crucial for mushroom life. Avoid disturbing this layer by digging around mushrooms or pulling up clumps of soil. A respectful attitude towards humus helps preserve ...

l), our knowledge of the turn-over of forest soil humus is very incomplete. This is particularly true of the organic matter in soil horizons below the humus layer.