One of the very first steps in the progression of lithofacies analysis (and, therefore, lithofacies formation), is the description and interpretation of available and conventional core data.

An important outcome of core descripting is the subdivision of cores into lithofacies, defined as classifications of a sedimentary sequence based on lithology (the study of the characteristics of rock), grain size, physical and biogenic sedimentary structures, and the stratification that relates to the depositional processes that produced them.

Lithofacies and lithofacies associations (groups of related lithofacies) are the basic units for the interpretation of depositional environments.