  The paper is devoted to the description of the reparametrization - invariant
dynamics of general relativity obtained by resolving constraints and
constructing equivalent unconstrained systems. The constraint-shell action
reveals the "field nature" of the geometric time in general relativity. The
time measured by the watch of an observer coincides with one of field
variables, but not with the reparametrization-noninvariant coordinate evolution
parameter.
  We give new solution of such problem, as the derivation of the path integral
representation of the causal Green functions in the Hamiltonian scheme of
general relativity.
