stratigraphicUnitRank

Given a predicate that represents a relationship or action between entities, generate a one-sentence description explaining its meaning.  
# Instructions
Focus on describing the relationship, not the entities themselves. 
# Response Format
Begin the description with \' Indicates...\'

Predicate: stratigraphicUnitRank

Indicates the hierarchical rank or level of a stratigraphic unit within a geological stratigraphic framework (e.g., formation, member, group).