GLG110_Lab1_Final(1) (1)

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California State University, Long Beach *

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Geology

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Apr 3, 2024

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pdf

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Uploaded by DukeLapwingMaster237

GLG110: Introduction to Geology and PLATE TECTONICS NAME: _ Layers of the Earth The planet Earth is divided into spheres that define different parts of our Earth system. The atmosphere is the layer of gases that surround out planet. The rest of the planet beneath our feet can be divided in one of two different ways. If divided by chemical composition, the Earth can be broken into layers that include the crust , which is the uppermost rocks and is less than 70 kilometers thick and forms less than 1% of the total volume. Beneath the crust is the mantle that makes up the majority of the planet (up to 85% of Earth’s volume). And the center of Earth is called the core . The crust is rich in potassium and silicon, while the mantle contains large abundances of iron and magnesium. The core is mostly made of nickel and iron. There is a second way to divide up the Earth’s layers that is based on the mechanical properties of the rocks. The uppermost rocks are rigid. If we hit them with a hammer, they’d break. We call this the lithosphere . It contains all of the crust and the uppermost portion of the mantle. Beneath the lithosphere is the asthenosphere. Asthenosphere means “weak” and these rocks flow like hot plastic. Asthenospheric rocks aren’t molten. They are just hot enough to flow when a force is applied, whereas lithospheric rocks are rigid and break. The asthenosphere is part of the mantle and the remaining mantle beneath is called the lower mantle . The core is also divided into the liquid outer core and solid inner core . Tectonic plates The lithosphere is what makes up Earth’s tectonic plates . Because the lithosphere is rigid and can hold together when force is applied to it, these lithospheric plates move around together. Because different parts of these plates are different compositions and temperatures, they are constantly sinking, moving, and colliding. All of these processes happen at the margins of the tectonic plates. In this exercise, you are going to use the characteristics of each type of plate margin or boundary to determine the type of plate boundaries present across the globe. There are three types of boundaries: divergent (moving away from each other), convergent (moving towards each other), and transform (sliding past). Plate “rides” On the asthenosphere
1.) Divergent plate boundaries : Divergent plate boundaries are the margins where two tectonic plates are moving away from each other, and the mantle beneath is moving up to the surface and crystallizing into new lithosphere, creating new parts of a tectonic plate. Divergent boundaries have many small to medium sized volcanoes , numerous earthquakes , and plates are moving in the opposite direction . The boundary is typically an elevated set of ridges with a central valley in the middle . Rocks along the edges of the boundary are very young (less than 10 million years old) , and get older further away from the margin. On your map, color . Example: The Mid-Atlantic Ridge in the middle of the Atlantic Ocean and the East African Rift are examples of divergent boundaries (see Globe 2 ), where two plates are moving apart.
STATION 1 VIRTUAL REALITY HEADSET: The image in the headset is from Thingvellir National Park in Iceland. If you look down the central valley, the rocks to the right are part of the North American tectonic plate. The rocks to the left are part of Europe (or the Eurasian tectonic plate). This location is one of the only places above the surface of the ocean where two tectonic plates can be observed at a divergent boundary. NOTE: There are ocean-ocean and continent-continent divergent boundaries. Although many of these have existed in the past, and many more will occur in the future, there are only a handful of active continent-continent divergent boundaries (known as rifts ) right now. In this exercise we will not split them out, so label all divergent boundaries the same. Convergent plate boundaries: Convergent boundaries are margins where tectonic plates are colliding. Convergent boundaries are characterized by many earthquakes and high relief mountain ranges . Rocks on one side of the boundary are typically less than 500 million years old . Plates are moving towards each other. There are two types of convergent plate boundaries: Continent-continent convergent boundaries: few to no volcanoes, many earthquakes, and between two continental plates. High elevation mountains. On your map, color . Continent-continent boundaries continued: Example: Himalayan Mountains of Asia are the result of the Indian and Eurasian tectonic plates colliding. See Globe 3.
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