Explain the advantage for melanin granules being located in the deep layer of the epidermis

UV radiation has a penetration power that can go down to the dermis, when UVA, or to the deepest layer of the epidermis, when UVB. UVA and UVB are the type of radiation that's the most potentially dangerous for DNA damaging to happen. Melanin absorbs the UV rays reducing the damage that these may produce to the living cells of the dermis and deeper, just bellow these granules.