Assertion: rhino's horn | /r/CapableOf | lose diameter
Facets:
value: by degradation of the keratin
type: CAUSE
value: due to ultraviolet light
type: CAUSE
value: as the layers age
type: TEMPORAL
Source sentences:
text: As the layers age, the horn loses diameter by degradation of the keratin due to ultraviolet light, drying out, and continual wearing.