A market economy, extended in continuous two-dimensional space, defined by the differential equations:
is studied, where φ denotes the vector field of traded commodities, λ the scalar field of commodity prices, q the scalar field of excess supply over demand, and k the cost of transportation. The generic theory of differential equations is used to topologically characterize those patterns that are structurally stable, and the transitions among them are then studied by the elliptic and hyperbolic umblic catastrophes.