Science 10: Lesson 4 Continental Drift Theory

Summary

In this Grade 10 science lesson, teacher Mom Marian Soriano explores plate tectonics, focusing on the geological activities at convergent, divergent, and transform boundaries. She discusses Alfred Wegener's theory of continental drift, supported by evidence like matching continental edges, fossils, rock formations, and ancient climates. Wegener's initial rejection by the scientific community due to a lack of understanding of the forces behind continental movement is also highlighted, emphasizing the journey from hypothesis to acceptance in scientific theories.

Takeaways

• 🌏 Plate boundaries are categorized into convergent, divergent, and transform fault boundaries, each with distinct geological outcomes.
• 🌋 Convergent boundaries involving oceanic and continental plates can result in volcanic arcs, trenches, and earthquakes.
• 🌊 Convergence of two oceanic plates can lead to volcanic island arcs, trenches, and underwater earthquakes that may trigger tsunamis.
• ⛰️ When two continental plates collide, it can result in the formation of mountain ranges and increased seismic activity.
• 🌅 Divergent boundaries, particularly when a continental plate diverges, can lead to the creation of rift valleys and the development of new ocean basins.
• 🔥 At oceanic divergent boundaries, magma rises due to thinning of the crust, forming oceanic ridges or underwater mountain ranges, and causing shallow earthquakes.
• ⏳ Alfred Wegener is credited with the hypothesis of continental drift, suggesting that continents were once part of a single landmass called Pangaea.
• 🧩 The continental drift theory is supported by evidence such as the jigsaw-like fit of continents, matching rock formations, and the presence of similar fossils across now-separated landmasses.
• 🌿 Fossil evidence, like the widespread distribution of the plant Glossopteris and the freshwater reptile Basosaurus, indicates that continents were once connected.
• ❄️ Glacial striations and coal deposits in Antarctica suggest that it had a tropical climate and was located near the equator in the past, supporting the idea of continental movement.
• 🌡️ The theory of continental drift was initially met with skepticism due to a lack of understanding of the forces responsible for continental movement and the perceived slow speed of such movements.

Q & A

What is the main topic of the lesson taught by Mom Marian Soriano?

The main topic of the lesson is the processes that occur along plate boundaries and the evidence supporting the continental drift theory.

What are the different outcomes of convergent boundaries?

Convergent boundaries can lead to the formation of volcanic arcs, trenches, and earthquakes when oceanic and continental plates converge, and volcanic island arcs, trenches, and underwater earthquakes when two oceanic plates converge. A collision zone with mountain ranges and earthquakes is formed when two continental plates converge.

What geological features are formed at divergent boundaries?

At divergent boundaries, a rift valley is formed when a continental plate starts to diverge, and as the plates continue to move apart, a sea or an ocean basin develops. Thinning of crust allows magma to rise and form oceanic ridges or underwater mountain ranges, and shallow earthquakes are also formed.

What are the characteristics of transform fault plate boundaries?

Transform fault plate boundaries are characterized by earthquakes, but unlike other boundaries, no plates are being destroyed, and thus, there is no formation of volcanoes and mountains.

Who is credited with the idea of continental drift theory?

Alfred Lother Wegener is credited with the idea of the continental drift theory.

What evidence from fossils supports the continental drift theory?

Fossils of the plant Glossopteris and the reptile Mesosaurus found in now-separated continents like South America, Africa, India, and Antarctica support the continental drift theory.

How do rock formations provide evidence for continental drift?

Rock formations in Africa that line up with South America, as if they were once part of a long mountain range, provide evidence for continental drift.

What is the significance of coal deposits found in Antarctica in relation to the continental drift theory?

The presence of coal deposits in Antarctica suggests that it once had a tropical climate and was located near the equator in the past, supporting the idea of continental drift.

What is the evidence of past glaciation across multiple continents?

Evidence of past glaciation in the form of glacial striations on continents like South America, Africa, India, and Australia indicates that these continents were once joined together.

Why was the continental drift theory initially rejected by the scientific community?

The continental drift theory was initially rejected because Alfred Wegener could not explain the force responsible for moving the continents and his estimated speed of continental motion was considered too high.

What is the supercontinent that all continents were once joined together to form?

The supercontinent that all continents were once joined together to form is called Pangea.