Question

Between 300 and 250 million years ago, plate movement assembled all the previously separated landmasses together to form the supercontinent Pangaea. The formation of Pangaea resulted in deeper ocean basins and a drop in sea level, causing shallow coastal areas to dry up. Thus, in addition to rearranging the geography of our planet, continental drift had a major impact on life on Earth. Use the accompanying diagrams and the information above to answer the following: a. Which of the following types of habitats would likely diminish in size during the formation of a supercontinent: deep-ocean habitats, wetlands, shallow marine environments, or terrestrial (land) habitats? Explain. b. During the breakup of a supercontinent, what would happen to sea level- would it remain the same, rise, or fall? c. Explain how and why the development of an extensive oceanic ridge system that forms during the breakup of a supercontinent affects sea level.

Short answer

a) Shallow marine environments and wetlands diminish. b) Sea level rises. c) Oceanic ridges increase sea floor elevation, raising sea levels.

Step-by-step solution

Analyze the Effect on Habitats During Supercontinent Formation

The formation of a supercontinent like Pangaea results in deeper ocean basins and a drop in sea level. This means that habitats which depend on shallow water or coastal regions, such as wetlands and shallow marine environments, would likely diminish in size due to drying up. On the other hand, deep-ocean and terrestrial habitats might not experience a significant decrease in size during the formation of a supercontinent.

Determine Sea Level Changes with Supercontinent Breakup

During the breakup of a supercontinent, the sea level would likely rise. As the supercontinent breaks apart, ocean crust production at mid-ocean ridges increases. This spreads and elevates the ocean floors, displacing water and causing a rise in sea level.

Explain the Impact of Oceanic Ridge Systems on Sea Level

The development of an extensive oceanic ridge system during the breakup of a supercontinent influences sea level by contributing to its rise. As these ridges form, they elevate the seafloor since new crust is being created, which increases the volume of the ocean basins and pushes water upwards, raising the sea level. The increased activity at ridges means more magma, expanding the crust and eventually raising the ocean surface.

Key concepts

Pangaea

Pangaea, often referred to as the supercontinent, was a massive landmass that brought together all the Earth's continents over 300 million years ago. This fusion of continents drastically altered the planet's geography. During its existence, vast ocean basins formed around it, leading to the drying up of shallow coastlines. This new configuration of land and sea played an important role in the Earth's climate and ecological systems. It also influenced the evolution and distribution of life forms. Coastal ecosystems like wetlands and shallow marine habitats were significantly reduced as they found themselves above sea level.

Continental Drift

Continental drift is the gradual movement of the continents across the Earth's surface through geological time. This movement is the result of tectonic plate interactions. Initially a controversial concept, it was first proposed by Alfred Wegener in the early 20th century. The drift led to the formation and separation of supercontinents like Pangaea, influencing geological and biological processes worldwide. As continents drift apart, climate zones and sea levels change, which in turn affects the habitats and evolution of species. This drift is a slow process, but over millions of years, it significantly reshapes the planet's structure.

Supercontinent Breakup

The breakup of a supercontinent is a crucial geological process in Earth's history. When Pangaea broke apart, it led to major changes on the planet. As the continents drifted away from each other, the tectonic activities increased along the oceanic ridge systems. The production of new oceanic crust at these ridges caused sea levels to rise as the seafloor spread and made the ocean basins shallower. Increased volcanic activity also played a part in altering the climate and ocean chemistry during this time. This process of breakup also initiated the creation of new marine environments.

Oceanic Ridge System

The oceanic ridge system is a continuous underwater mountain range, formed by plate tectonics during processes like the breakup of supercontinents. These ridges are caused by the upwelling of magma from the Earth's mantle, creating new oceanic crust as tectonic plates move apart. The mid-ocean ridges are one of the most dynamic and active features of our planet, responsible for seafloor spreading. As these ridges form, they affect sea level by increasing the ocean floor's elevation, causing displacement of water upwards, resulting in rising sea levels. They are central to understanding geological phenomena like earthquakes and volcanic eruptions.