  Geometrically a crystal containing dislocations and disclinations can be
envisaged as a `fixed frame' Cartan--Einstein space-time carrying torsion and
curvature, respectively. We demonstrate that electrons in defected graphene are
transported in the same way as fundamental Dirac fermions in a non-trivial 2+1
dimensional space-time, with the proviso that the graphene electrons remember
the lattice constant through the valley quantum numbers. The extra `valley
holonomy' corresponds to modified Euclidean symmetry generators.

Mesoscale and Nanoscale Physics;General Relativity and Quantum Cosmology