The word 'bio' stands for 'life' and weathering refers to the decay or ruin of anything. Thus biotic weathering refers to weathering that is caused by any form of life on earth. For instance, plant roots are the most common cause of weathering of rocks. Roots usually go very deep into creacks inside rocks in order to find water. In this process they cause the gaps within the rocks to become wider and wider. In due time the rocks are filled with huge cracks that keep getting wider and wider thus causing the weathering of the rocks. Other living agents that can contribute to biotic weathering are fungi, algae, microscopic plants and animals. Fungi and algae are responsible for the weathering of many plants when they cover them in order to get food from them.
