What evidence supports the theory of continental drift? Ever tried to put together a jigsaw puzzle?
It is pretty much the same for scientists trying to establish the theory of continental drift.
And they are constantly looking for evidence to support continental drift.
Thankfully, a wealth of data from rocks, fossils, and ocean floors has given us a fairly accurate picture of the jostling of the continents.
There is plenty of evidence to support the theory and it is often divided into geological evidence, Paleontological evidence, and geophysical evidence.
What Evidence Supports the Theory of Continental Drift?
The Theory of Continental Drift focuses on the supercontinent, Pangaea. It states that all of Earth’s continents originated from Pangaea.
They then split apart and drifted to their present-day locations over a period of millions of years.
For millions of years, earthquakes, volcanic eruptions, and the creation of new land masses have occurred due to the steady shifting of tectonic plates beneath the Earth’s surface.
The Theory of Continental Drift was a revolutionary concept that altered how scientists saw the Earth’s geological past and its subsequent evolution.
Is the Theory of Continental Drift Proven?
For a long time after Alfred Wegener’s 1912 proposal of the Theory of Continental Drift, scientists were skeptical of and critical of its validity.
However, throughout the 1960s and 1970s, the hypothesis acquired general support as more evidence was gathered and technology improved.
Moreover, it has since been modified into the more comprehensive Theory of Plate Tectonics.
Finding Evidence to Support the Theory of Continental Drift
When it comes to finding supporting evidence for the theory of continental drift, you can find experts dividing it into different categories.
So, what evidence supported the theory of continental drift?
- Geological Evidence
- Paleontological Evidence
- Geophysical Evidence
Learning More about Geological Evidence
You can actually find an abundance of geological evidence supporting the theory of continental drift.
For instance:
Fit of Continents
The idea that the land on Earth was once part of one single giant landmass was first posited by Alfred Wegener in 1930.
He proposed that after considering how they looked on maps as if they could be fit together like a jigsaw.
He hypothesized that all the continents were parts of a supercontinent, Pangaea, that had split and pieces had drifted away.
There is evidence supporting some of Wegener’s hypotheses, although continental drift is a little more complicated.
Rock Types and Structures
Wegener and others after him, looked at rocks and found 2,000-million-year-old cratons on separate continents.
Since they had the same composition, they surmised they must have formed in the same place at the same time, even though now they were an ocean apart.
The rock evidence suggested that entire mountain ranges that were once forced up as continents collided, could also be separated if the landmass the range stood on split.
The mountains of North American and Europe not only fit together but share an identical geological makeup.
Fossil Evidence
There is plant and animal fossil evidence too.
Fossils of Mesosaurus, a freshwater reptile, were found in Africa and North America and lystrosaurus, a lizard, in Africa, India, and Antarctica.
Cynognathus, another reptile, was found in South America and Africa. None are capable of swimming in an ocean.
Fact: Glossopteris, a fern, was found in Africa, South America, Antarctica, India, and Australia, and though wind plays a role, it is unlikely for seeds to survive the ocean.
More about Paleontological Evidence
Paleontological data, often known as the fossil record of organisms that once lived, can reveal crucial details about the development of life on Earth throughout time.
The idea that the continents were once joined and have since drifted apart is central to what is known as the Theory of Continental Drift, and paleontological data plays a crucial role in this context.
Distribution of Fossils
Worldwide, the distribution of fossil evidence supported the continental drift theory.
It was the only way to account for how identical lifeforms could be found fossilized thousands of miles apart separated by water.
If this were not the case, each species encountered would have had to have evolved in exactly the same way despite being on separate continents and counter to Darwin’s Theory of Evolution.
Similarities of Fossil Types
Examination of Mesosaurus fossils revealed it was a crocodile-type reptile from between 286 and 258 million years ago.
It was capable of swimming but incapable of surviving the saltwater of an ocean for a lengthy sea voyage.
Yet, the fossil evidence clearly points to the Mesosaurus found in Africa being physiologically the same as those found in North America.
Fact: Fossils Cynognathus that lived 250 million years ago were found in a band stretching across North America and Africa.
Ancient Climates and Habitats
The Glossopteris fossil evidence is distributed across the southern regions of five continents.
The distribution suggests that in the Early Permian, this shrubby tree fern, which was absent in the north, thrived in the south.
This finding supported the idea that the single giant supercontinent was not one homogeneous habitat, but several, with differing weather conditions and climates.
Matching up ancient glacial tracks provided proof that the continents were once connected.
The grooves lined up perfectly as they crossed the continent’s boundaries.
More about Geophysical Evidence
Measuring the Earth’s physical properties can reveal information about the planet’s make-up and history, a field of study known as geophysics.
And it has a lot to do with the theory of continental drift.
Seafloor Spreading
Although the hypothesis was that the continents drifted away, how was a mystery.
In 1960 geophysicist Harry Hess offered a new idea; rather than continents drifting, they were shifted on tectonic plates during mantle convection.
Seafloor spreading occurs at the edges of these plates where less dense material rises from the hot mantle as magma and cools forming a new lithospheric crust.
The newest and thinnest is towards the middle of the mid-ocean ridge.
Fact: Since the specific magnetism is set according to the Earth’s magnetic field as basalt cools, scientists confirm that seafloor spread is a continuous process.
Earthquakes and Volcanoes
Earthquakes and volcanoes happen at the edges of active tectonic plates such as around the Ring of Fire in the Pacific basin.
The plates collide and rub against each other causing seismic activity. Volcanism occurs at two types of the plate boundary, divergent and convergent but not at a transform boundary.
The Mid-Atlantic ridge is a divergent boundary, it has plates that are pulling away from each other. Volcanoes form as magma forces its way between them.
The Ring of Fire is at a convergent boundary. Colliding plates buckle up or are subducted down into the mantle softening and sliding under the opposing plate.
Magma rises around it and through it, solidifying into granite, the bedrock of the continents.
All this suggests that continents are constantly moving.
More about Supporting Theories
It is now possible to find many supporting theories related to continental drift.
For instance:
Plate Tectonics Theory
Inspired by ideas of continental drift, which is also evidence of it, plate tectonics theory accounts for how landmasses and volcanoes form very comfortably.
It is the dominant theory superseding continental drift.
It supports what we now know and understand about how the Earth’s lithosphere reacts and moves as it is recycled through the mantle via the processes of subduction and convection.
Mantle Convection Theory
The mantle convection theory posits that currents produced as part of the process of convection move the continents away from each other resulting in seafloor spreading.
It supports continental drift in that the continents move only not in the way a ship would through the surface of the water.
Evidence of Continental Drift from Modern Technology
These days, scientists study plate tectonics with ultra-modern technology.
A supercomputer has created sophisticated models of Pangaea and other supercontinents we now know came before it.
Paleontologists hope to produce the ‘most detailed map ever’ of the Earth’s resources.
Mining companies and oil prospectors are particularly interested since their products were laid down millions of years ago.
An Important Consideration
Until the 1950s, what happened on the seabed was relatively unknown.
Post-war oceanic research discovered that the magnetic field could flip leaving a magnetic signature in cooling rock magma.
It added to evidence that supported Wegener’s continental drift theory since rocks found on different continents all had the same magnetic signature.
Fact: We now know the mechanism of the drift, that it is the tectonic plates of the lithosphere moving on top of convection currents.
Takeaway
What evidence supports the theory of continental drift?
It is easy to notice that the Theory of Continental Drift has advanced greatly since Alfred Wegener first proposed it back in 1912.
In order to back up the theory that the Earth’s continents have moved and shifted over millions of years, scientists have scoured the globe in quest of evidence.
Evidence from the fields of geology, paleontology, and geophysics, such as earthquakes and volcanic eruptions, have all contributed to the consolidation of the idea of continental drift.
