NTR: age-depth model

[TrisSN]

Requested this from ENVO, and they recommended requesting from IAO. Here's the ENVO request: EnvironmentOntology/envo#857 (comment)

and in more detail:

NTR: age-depth model
Definition: a model used to relate the depth (of a sediment sample, for example) to its age, often derived in order to estimate the ages of depths between discretely sampled depths
Source: I wrote this myself because I couldn't find a clean definition, but I used this paper: https://doi.org/10.1029/2018PA003457 (and we have two papers dealing with age-depth models to be published in the next couple of months at Scientific Data)
Parent: possibly 'data transformation'?

[zhengj2007]

@TrisSN Does it fit better in OBI (http://obi-ontology.org/) domain?