alloformation noun1 •The fundamental allostratigraphic unit, which may be considered part of an allogroup and may be made up of smaller allomembers; A mappable stratiform body of sedimentary rock that is bounded by discontinuities.An alloformation may be completely or only partly divided into allomembers, if some useful purpose is served, or it many have no allomembers. — 1990 formsalloformations
