The
lithology of a
rock unit is a description of its physical characteristics visible at
outcrop, in hand or
core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of the gross physical character of a rock. It is the basis of subdividing rock sequences into individual
lithostratigraphic units for the purposes of
mapping and correlation between areas. In certain applications, such as
site investigations, lithology is described using a standard terminology such as in the European geotechnical standard
Eurocode 7.