What is biological weathering?
Biological weathering is when plants, animals or anything that comes from nature breaks the rocks into tiny pieces. Most of the time, plants and animals are the common factors to biological weathering. Humans can also contribute to this unknowingly/knowingly for example: accidentally kicking rocks and breaking them or mining them in search of ores. Some of plants that need more nutrients and water from the soil will probably do this more often as they go deeper than other plants.
How is it formed?
For plants, when their roots try to go deeper and they encounter a rock, they choose the fastest way through, forcing its way into the rock and splitting it in half. The roots then repeat this to any rocks it comes across again. Smaller plants can do these as well, albeit on a smaller scale. Ivies, lichens (not moss), vines and moss (moss). Ivies tend to dislodge pieces of rocks from buildings as they grow upwards. Lichens and moss weather rocks slower than other plant roots.
Where is it found?
This type of weathering is normally found near areas where there are plants and animals. It can also be found near places like coal mines and tin mines where the contributing factor are humans.
Information taken from
http://www.geography.learnontheinternet.co.uk/topics/weathering.html
http://www.geography.learnontheinternet.co.uk/topics/weathering.html