Question

What hypothesis states that continents slowly moved to their present positions on Earth? A) subduction C) continental drift B) erosion D) seafloor spreading

Short answer

The hypothesis is Continental Drift (C).

Step-by-step solution

Understanding the Question

We need to determine which hypothesis describes the movement of continents to their current locations on Earth over time.

Identify the Terms

The question provides four terms related to geological processes: subduction, continental drift, erosion, and seafloor spreading. We need to identify the one associated with the movement of continents.

Define Each Term

- Subduction: This process involves one tectonic plate sinking beneath another at convergent boundaries. - Continental Drift: A hypothesis proposed by Alfred Wegener stating that continents have slowly moved to their current positions. - Erosion: The process by which surface materials are worn away and transported by natural forces such as wind or water. - Seafloor Spreading: The process of new oceanic crust forming at mid-ocean ridges and slowly moving away.

Match the Hypothesis

The term 'continental drift' directly relates to the hypothesis that continents have moved over geological time to their present locations. This hypothesis is consistent with the question's description.

Conclusion

Based on the definitions, the hypothesis that pertains to continental movement is the Continental Drift hypothesis. Therefore, the correct answer to the question is C) Continental Drift.

Key concepts

Plate Tectonics

The concept of plate tectonics is a cornerstone of geology that explains the structure and movement of Earth's surface. This theory emerged after the concept of continental drift, expanding upon Wegener's initial ideas. It explains how Earth's lithosphere, the outer shell, is divided into several large and small pieces known as tectonic plates. These plates float and move on the softer, semi-fluid asthenosphere beneath them.

Major movements in these tectonic plates are responsible for many geological phenomena. They cause

• Earthquakes
• Volcanoes
• Mountain building
• Ocean trench formation

At convergent boundaries, two plates collide, and one may sink beneath the other, a process known as subduction. At divergent boundaries, plates pull apart, allowing new crust to form, such as in seafloor spreading at mid-ocean ridges. Transform boundaries, on the other hand, slide past each other, often causing earthquakes.

Understanding plate tectonics helps us predict geological activity and comprehend past continental configurations.

Tectonic Plates

Tectonic plates are massive slabs of Earth's lithosphere which fit together like a jigsaw puzzle covering the planet's surface. These plates are not static but are constantly moving, albeit very slowly, at rates of a few centimeters per year. This movement is driven by forces associated with heat from the Earth's internal processes, such as mantle convection.

The Earth is currently segmented into about seven major tectonic plates and several smaller ones, including

• Pacific Plate
• North American Plate
• Eurasian Plate
• Indo-Australian Plate
• African Plate
• South American Plate
• Antarctic Plate

As these plates interact at their boundaries, they give rise to the majority of Earth's seismic and volcanic activities. The creation, destruction, and sliding of tectonic plates have shaped landscapes over millions of years, leading to the formation of continents, mountain ranges, and ocean basins.

The study of tectonic plates gives scientists insights into past geological events and clues about future changes in Earth's surface.

Alfred Wegener

Alfred Wegener was a pioneering German meteorologist and geophysicist who introduced the groundbreaking hypothesis of continental drift in 1912. Wegener suggested that continents were once joined together in a supercontinent he named Pangaea and have since drifted apart to their current positions.

Wegener's theory was based on several pieces of evidence, such as

• Matching shapes of continental coastlines
• Fossil correlations across continents
• Similar rock formations and mountain ranges on different continents

Despite these compelling observations, Wegener's hypothesis was initially met with skepticism by the scientific community because he could not provide a mechanism for the movement of continents.

However, with the advent of the theory of plate tectonics in the mid-20th century, Wegener's ideas gained significant support. The concept of moving tectonic plates provided the missing mechanism, validating his vision of drifting continents and transforming our understanding of Earth's dynamic nature.