Northeast region, Mexico |
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Paleontology and geologyThe Precambrian: Precambrian rocks in the Northeastern Region of Mexico formed as volcanic islands, oceanic sediments, and part of the continent of Gondwana, an ocean away from Laurentia (ancient North America). These igneous, sedimentary, and metamorphic rocks date back to 1.0 Ga. They reached their present location by the movement of tectonic plates. The Paleozoic: Paleozoic rocks in the Northeastern Region of Mexico were deposited in shallow to deep seas off the coast of Gondwana. These seas were home to many different invertebrates, some of which built up reefs. Over time, Gondwana moved closer to Laurentia, and by the end of the Paleozoic, the two continents collided to form the supercontinent Pangea. This collision folded and faulted rocks, pushing up some areas and dropping others into basins. It also brought rocks from the margin of Gondwana to their present location in the eastern part of this region. To the west, shallow to deep seas swept out to the open ocean, where there were many volcanic islands. The Mesozoic: Pangea broke apart in the Mesozoic, and the Gulf of Mexico opened up in the east. In the west, subduction added volcanic islands and slices of oceanic crust to the continent. This activity brought magma near the surface, forming volcanoes and huge blocks of granite below older rocks. Forests, swamps, and lakes covered the land, where many different dinosaurs, other reptiles, and early mammals lived. By the end of the era, shallow seas flooded the eastern part of this region, and the western part was pushed up. The shallow to deep seas were filled with invertebrates, bony fish, sharks, and marine reptiles. The Cenozoic: In the Cenozoic, interactions between the oceanic and continental plates in the west pushed up much of the region and generated significant volcanism. Basins and mountain ranges formed in the north, volcanoes erupted lava and ash over the surface, and many rocks were folded and faulted. The seas on both coasts were filled with many vertebrates and invertebrates. On land, forests, grasslands, and lakes hosted a wide range of mammals from North and South America, as well as invertebrates, reptiles, amphibians, fish, and birds. |
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