The term ‘‘facies’’ has been used in various geological disciplines
with varying meanings. In 1838, Gressly was the first to use the
term to designate the ‘‘aspect’’ of a group of rocks. Some authors
apply the term to eminently descriptive aspects, whilst others
use it to refer to generic aspects. Others still, use the term for both
types of criteria. Back (1960, 1966) took into account the concept
of geological facies (meaning similar lithology and depositional
history) and defined the term ‘hydrochemical facies’ to denote
‘‘the diagnostic chemical aspect of water solutions occurring in
hydrologic systems,’’ which ‘‘reflect the response of chemical processes
in the lithologic framework and the pattern of water flow in
it’’. He applied the idea to groundwater solutes, illustrating for the
first time how the solutes changed along a flowpath (in Baedecker
and Wood, 2009).