continental drift It is a scientific theory of great importance in biology, geology and geography, which explains how the Earth’s continents have moved and changed their position over millions of years. If you wonder what this is, then we will explain everything about it.
Concept and meaning of continental drift
It is a geological concept that refers to the slow and gradual movement of tectonic plates on the earth’s surface. This process was first proposed by the German scientist Alfred Wegener in the 1910s, who suggested that Earth’s continents had coalesced into a supercontinent called Pangea, which broke apart and moved toward its current configuration.
Wegener based his theory on evidence that the continents fit together like puzzle pieces and that there were geological and paleontological similarities between those separated by oceans, implying that they had been together at a time in the past.
Over time, the continental drift theory has expanded and been supported by modern scientific research. The continents are known to move slowly at a rate of a few centimeters per year due to the movement of tectonic plateswhich are large blocks of the Earth’s crust that float on top of the Earth’s hot, mobile mantle.
What is the origin of continental drift?
Is found in plate tectonics, which is the geological theory that explains how the Earth’s lithosphere (the solid outer layer of Earth) moves and changes over time. According to the theory of plate tectonics, the lithosphere is made up of several rigid phases that move slowly over the asthenosphere, which is the layer of the Earth’s mantle that lies below the lithosphere and is more plastic and deformable. These move impelled by the convection of the hot material of the mantle, which produces currents of the same and that drag the plates on the surface of the Earth.
When two separate, a fault zone or mid-ocean ridge is created at the bottom of the sea. On the other hand, when converging, one plate slides under the other in a subduction zone, and this gives rise to the formation of mountain ranges and volcanoes. These processes can cause the continents to separate or join together, and explain how the geology of the earth it has changed over time.
Who proposed the theory of continental drift?
It was proposed by the German geologist and meteorologist Alfred Wegener in 1912. He suggested that, in the primordial past, the continents now separated by great distances were united in a single department known as the supercontinent called Pangaea.
Wegener proposed this theory after observing that the eastern coast of South America and the western coast of Africa seemed to fit together like puzzle pieces. He also noted that certain fossil plants and animals were common on both continents, suggesting that were connected in the past. Although Wegener’s continental drift theory was initially met with skepticism and rejection, in subsequent decades it was supported by additional geological and paleontological evidence.
What are the fundamentals of continental drift?
It is based on various geological, paleontological, and climatic evidences that suggest that the continents have shifted position over geological time. Some of the basics of continental drift are the following:
- lace of the continents: One of the first observations that led Wegener to propose the theory was that the edges seemed to fit together like puzzle pieces.
- geological similarities: It was also observed that the rocks and geological structures were similar. For example, those of the Appalachian mountain belt in North America are similar in composition and age to the stones of the Caledonian Mountains in Scotland and the mountains of Norway.
- Fossil Distribution: this fact also supports the theory of continental drift. For example, remains of reptiles of the genus Mesosaurus were found in Africa and South America, suggesting that these continents were once connected.
- Paleoclimatic evidence: The distribution of coal deposits and ancient glaciers also assumes that the continents have moved over time.
- rock magnetism: Orientation on the ocean floor provided one of the most conclusive tests of the theory of continental drift. These are formed from lava that solidifies when it emerges from mid-ocean ridges. This magma contains magnetic minerals that align with the Earth’s magnetic field at the time of its formation. The studies showed that the polarity of the rocks changed over time, suggesting that the continents had moved.
What are the stages of continental drift?
It is a geological process that has occurred over millions of years, and has been divided into several epochs. The main stages of continental drift are the following:
- The formation of Pangea: about 300 million years ago, all the world’s continents were united in a supercontinent called Pangea.
- The fragmentation of Pangea: about 200 million years ago, Pangea began to divide due to tectonic activity on Earth. The forces of plate tectonics began to move the continents, creating a series of large fissures that filled with seawater, forming new oceans.
- The separation of the continents: As the fragmentation of Pangea continued, they began to move smoothly in opposite directions.
- The formation of the current oceans: as the continents separated, new seas began to be generated. For example, the Atlantic originated as North America and Europe receded from each other.
- The current configuration of the continents: have continued to move since the breakup of Pangea, but are presently in a form that is quite similar to that which existed about 50 million years ago.
The Cambrian period is one of the most important geological times in the history of the Earth, since marks the start of the ‘explosion’ of life on the planet. This era is within the Paleozoic era and extends from 41 million years ago to about 485 million years. During the Cambrian, the continents were still joined at Pangea, but tectonic activity was causing some of them to drift apart. The climate was hot and humid, and most of the Earth was covered by shallow seas.
During this period, many crucial geological events occurred that had a significant impact on the formation and evolution of life on Earth. One of the most important events was the sudden appearance of a great diversity of complex multicellular organisms, including animals with shells and exoskeletons. This period also saw the rise of many groups of species that still exist today, such as trilobites and mollusks.
The Devonian period is a geological time that is within the Paleozoic era, and extends from 416 million years ago to about 359 million years. During this period, the continents were still united in the supercontinent of Gondwana, although they were starting to drift apart.
During the Devonian, life on Earth experienced significant changes and evolutions. In the seas, coral reefs became crucial structures and ecosystems, and the first bony sharks and fish appeared. In rivers and lakes, terrestrial plants and animals developed, including insects, amphibians, and reptiles.
One of the most significant events of the Devonian period was the expansion of forests, which modified weather and atmosphere from Earth, since land plants absorbed carbon dioxide and produced oxygen. This led to the creation of an ozone layer in the atmosphere, which allowed terrestrial organisms to get out of the water and colonize the continents.
The Permian period is a geological epoch that is within the Paleozoic era, and extends from 299 million years ago to about 251 million years. Important changes originated both in life and in the configuration of the continents. During the Permian, the continents continued their separation process, and had divided into two large supercontinents: Laurasia to the north and Gondwana to the south. The Permian climate was hot and dry, and the oceans had high salinity due to the separation of the continents and the lack of freshwater flow.
As for life, it was a period of major mass extinctions, which are known as the Permian-Triassic, which wiped out around 96% of marine species and 70% of terrestrial species. This mass extinction was linked to intense volcanic activity that released large amounts of carbon dioxide and other greenhouse gases into the atmosphere, causing global climate change and significant change in Earth’s ecosystems.
The Eocene is a geological period that is within the Cenozoic era, and extends from 56 million years ago to about 33.9 million years. In this period, the continents continued their process of separation and were configured in a disposition very similar to current.
During the Eocene, the Earth experienced a weather Warm and wet, and the oceans were much warmer than at present. The global average temperature was about 15 degrees Celsius warmer than modern. This allowed the development of a great diversity of flora and fauna, including the appearance of many of the animal groups that can be seen today.
The Pleistocene is a geological period that is within the Cenozoic era, and extends from 2.6 million years ago to about 11,700 years ago, when the the end of the last ice age. During this time, the Earth experienced important climatic fluctuations, with the presence of long periods of glaciation and others of warmer climates, known as interglacials.
As the ice ages progressed and receded, the continents also experienced changes in their topography, with the erosion and sedimentation of large amounts of rock and sediment, giving rise to the formation of valleys, mountains, and sedimentary basins. During the Pleistocene, the evolution of many of the animal and plant species that we know today took place, as well as the appearance of the first humanswho began to develop tools and live in organized communities.