The Grand Canyon It is a huge throat located in Arizona, in the United States, delimited by rocky walls with bright colors and naturally dug by the Colorado river in the last 60 million years. Up to 30 km widewinds through the plateau for one Length of about 350 km. The erosive action of the water brought to light a thickness of Stratified rocks That passes the kilometer and a half. These rocks have not always been where we see them now, but in ancient times they constituted a seabed which has been raised several times by the movements of the lithospheric plaques. The Grand Canyon does not only constitute a unique landscape beauty, but also a Archive of geological and biological events who followed one another over the course of the last 2 billion years.
How the Grand Canyon formed was formed
The Colorado plateau region, which today exceeds the kilometer and a half altitude, About 2.5 billion years ago constituted a seabed. On this seabed, one on the other, thick layers of sediments were deposited, inframed by the lava flows of the volcanoes of the area, which over time turned into rocks. A billion and a half years agothe enormous compressive forces inside the litosphere bent the rocky layers of the seabed until the lifting and originating mountains. For hundreds of millions of years, then, erosion acted on the reliefs by paving them. Subsequently, these plains were invaded by the sea again and other layers of sediments have covered them. About a billion years agothe layers have suffered a further liftingwith the formation of mountain ranges. Erosion has flattened these reliefs, originating the plateau, while the lifting accelerated (in the last 75 million yearsthe busty pushes raised the area of about 2500 m). In the meantime, Colorado together with his tributaries began to began affect the Grand Canyon And still today erosion accompanies the lifting of the region.
The geology of the Grand Canyon
Along the Grand Canyon they stand out Twelve main layers Of very different colors, variables between red and gray, which have formed in different times and environments. The layers have filed horizontally one on the other in chronological succession. This means that the most recent ones are higher, and vice versa. These rocks contain traces of ancient organisms, in the form of fossils. It is mostly of marine bodiesbut there are also traces of insects and plants such as ferns.
The deeper layer of the Grand Canyon dates back to the precarious, well 2 billion years ago. Constitutes the remains of the first mountain chains, whose drainage and deformed rocks They are the result of the action of the high pressures on the sedimentary rocks of the ancient seabed. These rocks have been flattened by erosion and, always in the foreclosure, when the sea submerged them again, covered by limestone sediments containing algae fossils. The second lifting of a billion years ago He then fractured and inclined them. Erosion canceled any testimony of the time interval that ranges from a billion years ago 500 million years ago. The rocks that cover the limestones of the precariousness date back to Paleozoicwhich begins 550 million years ago and which most of the strata visible along the Grand Canyon belongs. It is Gray and red sandstone limestones who show an alternation of fossils of marine and continental bodieswhich testifies to the succession of phases of submergence and emergence from the sea. The upper layer dates back to about 270 million years ago And it is rich in remains of corals and sponges. Of the Mesozoic era, which follows the Paleozoic one, few testimonies remain due to the erosion that removed the upper strata. In the future, while the plateau will continue to rise, erosion will inevitably evite other precious testimonies in the history of our planet.
