Question

How does the fit of the coastlines around the Atlantic support continental drift? (B)

Short answer

The fit of the coastlines around the Atlantic, particularly between the eastern coast of South America and the western coast of Africa, supports the theory of continental drift by showing that these continents were once connected as a large landmass called Pangaea. Their congruent patterns resemble puzzle pieces that fit together, indicating their past connection. This evidence, combined with geological and biological correlations, demonstrates the validity of continental drift as a scientific theory.

Step-by-step solution

Familiarize yourself with the concept of continental drift

Continental drift is the hypothesis that the continents have moved away from one another over time. This idea was first proposed by Alfred Wegener in 1915, suggesting that the continents were once connected as a large landmass called Pangaea, which began breaking apart and drifting around 200 million years ago.

Identify the coastlines around the Atlantic

The continents surrounding the Atlantic Ocean are mainly Africa, South America, North America, and Europe. Pay particular attention to the western coastline of Africa and eastern coastline of South America, as well as the eastern coastline of North America and the western coastline of Europe.

Observe the matching patterns

If you place these continents' coastlines side by side, it is noticeable that they fit together like puzzle pieces. The congruent patterns, particularly between the eastern coast of South America and the western coast of Africa, indicate that these continents were once connected, providing support for the continental drift hypothesis.

Consider evidence beyond geography

While the fit of coastlines is compelling, it isn't the only evidence for continental drift. There are also geological and biological indicators, such as similar rock formations and fossils found on separate continents, which further support the idea that these landmasses were once connected.

Explain how the fit of coastlines supports the theory of continental drift

The matching shapes of the Atlantic coastlines serve as supporting evidence for the continental drift theory since it suggests that these continents were once part of a larger landmass and have moved away from their original positions over millions of years. This fit is especially evident between South America and Africa, strongly indicating their past connection. This evidence, along with geological and biological correlations, helps demonstrate the validity of continental drift as a scientific theory.

Key concepts

Pangaea

Pangaea was a supercontinent that existed approximately 200 million years ago. Imagine a time when all the land on Earth was connected as a single massive landmass. That was Pangaea. This concept is central to the idea of continental drift. The term "Pangaea" itself means "all lands" in Greek, symbolizing how it encompassed almost all the Earth's land surface. According to Alfred Wegener's hypothesis, Pangaea began to break apart due to tectonic forces, leading to the drifting of continents to their current positions. Understanding Pangaea helps us visualize how the continents once fit together. Like pieces of a giant puzzle, continents that now border the Atlantic Ocean were once snugly connected in Pangaea. By tracing back these movements, scientists can gain insights into the geological history of Earth.

geological indicators

Geological indicators are crucial pieces of evidence that support the theory of continental drift. These indicators refer to geological features or phenomena that are consistent across different continents.

• Matching Rock Formations: Similar rock layers and geological structures found in different continents suggest a shared origin. For example, the Appalachian Mountains in the eastern United States align with their counterparts in Greenland and Europe, indicating they once formed a continuous range.
• Similar Mineral Deposits: Identical mineral deposits and mountain chains that extend across continents further illustrate their former connection.

These geological clues serve as evidence that continents we see today, such as Africa and South America, were once joined. The exact alignment of these geological features provides a tempting glimpse into Earth's past, affirming that significant movement has occurred over hundreds of millions of years. When studying continental drift, geological indicators are important to confirm that the physical features we observe are not mere coincidences but rather remnants of a time when continents were united.

fossil evidence

Fossil evidence offers another compelling line of support for the idea of continental drift. By studying fossilized remains of plants and animals, scientists can trace their distribution across different continents.

• Identical Species Fossils: Fossils of the same species have been found on continents now separated by vast oceans. The Mesosaurus, a freshwater reptile, is a classic example, with fossils discovered both in South America and Africa. This suggests that these continents were once joined.
• Plant Fossils: Plant fossils of the same type, such as Glossopteris, found in regions as far-flung as Australia, South Africa, and India, further corroborate that these areas were once connected.

The presence of similar fossils widely distributed across the continents suggests shared habitats that existed when the landmasses were part of Pangaea. Fossil evidence hence serves as a biological link that supports the geological and geographic clues of continental drift. By uncovering and studying these fossils, scientists strengthen the case for continental drift, revealing connections that transcend current geographical barriers.