The cones are aligned along easterly or northeasterly lineaments which correlate with geological structures in the basement, and appear to reflect the tectonic stresses underground. Among these lineaments is the La Carbonilla fracture which runs in east-west direction and crops out in the eastern part of the field; in the central sector it is hidden by the caldera and in the western it is buried by lava flows. The La Carbonilla fracture is a fault that appears to have been an important influence on the development of the Payún Matrú complex in general. Fissural ridges and elongated chains of vents and cones highlight the control that lineaments exercise on the volcanic eruptions. In the summit area, pumice cones are aligned along the caldera rim.