Paleontology and geologyDevonian rocks in the Southeastern Region of Mexico were deposited on the continental shelf, slope, and ocean basin off the coast of Gondwana. They include limestones, sandstones, and shales, as well as igneous rocks that formed from volcanic eruptions on the ocean floor. By the Middle Devonian, Gondwana began to move toward Laurentia as subduction closed the ocean that separated them. This movement pushed shallow to deep marine rocks up against the continent, while it pulled others underneath where the heat and pressure altered them significantly. Subsequent collisions altered these rocks even more. Most Devonian rocks have been eroded or buried and the few remaining exposures are too small to appear on this map. Some may be shown on the map of undifferentiated Paleozoic rocks or on other more detailed maps. |