The interaction of light with Cholesteric Liquid Crystals (CLC) in the presence of time dispersion, magnetooptical activity and absorption is considered. The magnetooptical activity leads to the waves irreversibility, i.e. to the absence of center of symmetry for the surface of wave vectors and other surfaces, characterizing the direction dependence of optical properties (the nonequivalency of the forward and backward directions of propagation occurs). The waves irreversibility effects in CLC and their influence on the geometry of the Bragg reflection are considered.