Let A be an abstract
stratification. Assume that every stratum X is a riemannian manifold. We first
give some conditions, under which it is possible to endow A with a suitable
metric extending a well known technique of riemannian manifolds. Then
stronger conditions are introduced in order that the metric space A becomes a
G-space. An abstract stratification with all the above conditions is called an
abstract riemannian stratification. Whitney stratifications are, in a natural way,
riemannian.