Stress fields.

The stress state at a point in the crust can be specified by describing the orientation and magnitude of the three principal stresses. It is not uncommon in structural geology that a depiction of the three principal stresses is used to implicitly or explicitly infer a homogenous stress field within the crust. This is an approximation or an assumption, and it is useful to remind ourselves that homogenous stress fields are a simplifying fiction. Stress fields exist due to increasing overburden with depth (lithostatic gradient), due to small and large scale topography, due to inhomogeneties and discontinuities in the crust (e.g. faults), due to openings (tunnels), due to intrusions, and due to variable plate boundary conditions. Stress fields in turn determine the patterns of structures that result. It is therefore insightful to consider some stress fields.

Student entries on stress fields (forthcoming):

Some relevant references: