  We construct calibrated submanifolds of R^7 and R^8 by viewing them as total
spaces of vector bundles and taking appropriate sub-bundles which are naturally
defined using certain surfaces in R^4. We construct examples of associative and
coassociative submanifolds of R^7 and of Cayley submanifolds of R^8. This
construction is a generalization of the Harvey-Lawson bundle construction of
special Lagrangian submanifolds of R^{2n}.
