At Motozintla, the fault bounds the Jurassic Todos Santos Formation
to the north and Permic crystalline rocks of the Chiapas Massif to the
south. Therefore, the Motozintla region is subject to a simple shear evidenced
by NE–SW oriented normal faults, exposed at the south of the
Xelajú Grande River, and NW–SE thrust faults, to the north of the river.
The two sets of faults are dominated by left lateral movements evidenced
by triangular facet structures