sentences: an example of weathering is a plant root growing into a crack in rock & a tree is a kind of plant ->  a tree's root growing into a crack in rock is an example of weathering  a plant is a kind of organism & a tree is a kind of plant ->  a tree is a kind of organism  a tree's root growing into a crack in rock is an example of weathering & a tree is a kind of organism ->  a tree's root growing into a crack in rock is an example of organism causing the weathering  a tree's root growing into a crack in rock is an example of organism causing the weathering & organic weathering means organisms cause the weathering of rocks -> a tree's root growing into a crack in rock is an example of organic weathering