Bone weathering is the physical and chemical breakdown of bone that happens after death as the remains are exposed to the environment over time. It shows up on the bone surface as cracks, flaking, and eventually powdering as the outer cortex dries, expands and contracts, and is acted on by sun, wind, moisture, soil chemistry, and soil fauna. The extent and pattern of these surface changes provide a relative timeline: more advanced weathering generally indicates longer exposure, so specialists use weathering stages to estimate time since death for skeletal remains when soft tissues are gone and other PMI clues are limited. Of course, this process depends a lot on the environment—climate, burial conditions, moisture, and soil chemistry all influence the rate and appearance of weathering—so assessments must be grounded in environmental context and reference data. This is why describing bone weathering as surface cracking and flaking from environmental exposure, with extent helping infer time since death for skeletal remains, is the best fit. Other statements mix in features of decomposition or color changes or mineral loss that aren’t the defining aspects of weathering.