Definition of upper

i. Pertaining to rocks or strata that are normally above those of earlier formations of the same subdivision of rocks. The adjective is applied to the name of a chronostratigraphic unit (system, series, stage) to indicate position in the geologic column and corresponds to late as applied to the name of the equivalent geologic-time unit; e.g., rocks of the Upper Jurassic System were formed during the Late Jurassic Period. The initial letter of the term is capitalized to indicate a formal subdivision (e.g., 'Upper Devonian') and is lowercased to indicate an informal subdivision (e.g., 'upper Miocene'). The informal term may be used where there is no formal subdivision of a system or series (counterpart of lower).

Compare with: lower, middle

Ref: AGI

ii. See: up hole