Monokline

A monocline is a structural feature in geology consisting of a single bend or flexure in otherwise uniform rock layers. Across the hinge line, the strata show an abrupt change in dip, but the beds on either side generally continue dipping in the same overall direction. This produces a step-like profile on the surface and in cross sections rather than a closed, cylindrical fold such as an anticline or syncline.

Formation and causes can vary. Monoclines often form where a relatively rigid block of rock is tilted or uplifted by faulting adjacent to the block, creating a vertical to steeply dipping hinge. They can also arise from large-scale flexural bending of sedimentary sequences, differential compaction, or the intrusion of igneous bodies that warp surrounding rocks. In some settings, multiple monoclines may occur in a regional faulting or tectonic regime.

Identification relies on field observations and geologic mapping. A monocline is recognized by a linear or gently curved hinge line where the dip of the rock changes abruptly. The beds on both sides typically dip in the same dominant direction, but with different gradients, giving a characteristic step-like stratigraphic section.

Geologic significance includes the potential to host structural traps for hydrocarbons, as changes in dip can influence fluid flow and reservoir geometry. Monoclines are common in foreland and rift basins and are studied in structural geology to understand local tectonics, faulting patterns, and the history of deformation in a region.