 Geomorphic offset-age relation

A marker that starts with zero offset and accumulates displacement at a constant fault slip rate $v$ has age $t=d/v$. More generally $d={\int }_0^{t}v(s)ds$. The inferred age belongs to the establishment, abandonment or last resetting of that particular marker. A channel incised into an alluvial fan can be younger than the sediment it cuts. Uncertain channel correlation, erosion, distributed slip and time-variable rates require corresponding age uncertainty; a numerical ratio alone does not date a fan’s deposition.