Explain what causes mechanical weathering and chemical weathering. , i really don't ! i will mark a !

Ice wedging, pressure release, plant root growth, and abrasion can all cause mechanical weathering. in the cracks and pores of rocks, the force of its expansion is strong enough to split the rocks apart. 
Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts.
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