  By embedding Einstein's original formulation of GR into a broader context we
show that a dynamic covariant description of gravitational stress-energy
emerges naturally from a variational principle. A tensor $T^G$ is constructed
from a contraction of the Bel tensor with a symmetric covariant second degree
tensor field $\Phi$ and has a form analogous to the stress-energy tensor of the
Maxwell field in an arbitrary space-time. For plane-fronted gravitational waves
helicity-2 polarised (graviton) states can be identified carrying non-zero
energy and momentum.
