  Making use of the fibre bundle theory to describe metric-affine gauge
theories of gravity we are able to show that metric-affine gauge theory can be
reduced to the Riemann-Cartan one. The price we pay for simplifying the
geometry is the presence of matter fields associated with the nonmetric degrees
of freedom of the original setup. Also, a possible framework for the
construction of a quantum gravity theory is developed along the text.
