Faults started to appear at this time due to epeirogenic movement, vertically lifting and lowering the surface.

Epeirogenic movement can be permanent or transient.

Epeirogenic movement has caused the southern Rocky Mountain region to be uplifted from 1300 to 2000 m since the Eocene.

In geology, epeirogenic movement (from Greek epeiros, land, and genesis, birth) refers to upheavals or depressions of land exhibiting long wavelengths and little folding apart from broad undulations.

In contrast to epeirogenic movement, orogenic movement is a more complicated deformation of the Earth's crust, associated with crustal thickening, notably associated with the convergence of tectonic plates.

Thus the major cyclic changes in Jurassic sedimentation (and possibly even the changes of faunal and floral evolution) have been blamed on eustatic changes in sea-level, and these in turn on epeirogenic movements on the ocean floor.