When the walls of the excavations are to be kept vertical and in order to protect the safety of. workmen, the general public, this or other work or structures, or excavation walls, or pipe. installation including ma terials encountered in the excavation which have a tendency to slough.
Hierarchy of Living Things. Biological organization, or the hierarchy of life, is the hierarchy of complex biological structures and system that define life using a reductionistic approach. The traditional hierarchy, as detailed below, extends from atoms (or lower) to biospheres.
hierarchy - a series of ordered groupings of people or things within a system; put honesty first in her hierarchy of values. 1  celestial hierarchy - the collective body of angels. 2  data hierarchy - an arrangement of data consisting of sets and subsets such that every subset of a set is of lower rank than the set. taxonomy - a classification of organisms into groups based on similarities of structure or origin etc.