  An effective mathematical framework based on Presymplectic Geometry for
dealing with the "phase space picture" of timeless dynamics in General
Relativity is presented. In General Relativity, the presence of the scalar
Hamiltonian constraint which vanishes leads to the problem of time, which can
be solved, up to an extent by adopting a timeless formalism. This has been done
by Carlo Rovelli and Julian Barbour et al. In this paper we present a phase
space reformulation of Barbour's theory. The Presymplectic dynamics of general
totally constrained, reparametrization invariant theories is developed, then
applied to Jacobi mechanics, relational particle mechanics and the dynamics of
the free relativistic particle.
