Earth Science Quiz 7th Grade 2.2

During a science class, Maya and Henry were discussing the layers of the Earth. Which of the following statements best describes the outer core?

• It is the outermost layer of Earth, made of solid rock.

• It is the liquid inner layer of Earth, made of metals at extremely high temperatures.

• It is the solid inner layer of Earth, made of metals at extremely high temperatures.

• It is the middle layer of Earth, made of rock which varies in temperature and thickness.

Answer explanation

The outer core is a liquid layer composed mainly of molten metals, such as iron and nickel, and exists at extremely high temperatures. This distinguishes it from the solid inner core and the outermost solid crust.

Ethan and Grace are discussing the processes that form the different rocks near mountains and lakes. Which choice below compares the formation of rocks at these locations?

• Mountains push weathered rocks underneath tectonic plates to form sedimentary rocks inside the mantle. Rivers erode igneous rocks over time to form metamorphic rock.

• Sedimentary rock is formed from the heat and pressure in between tectonic plates to form mountains. Rivers deliver weathered rock to lake beds and form igneous rock over long periods of time.

• Metamorphic rock is formed by heat and pressure of tectonic plates is then pushed up to form mountains. Rivers deliver weathered rocks into lake beds forming sedimentary rock as more layers are added.

• Igneous rock is formed by volcanoes releasing magma from the mantle, the rock cools and piles up forming a mountain. Rivers direct water to cool magma underground forming metamorphic rock under lake beds.

Answer explanation

The correct choice explains that metamorphic rock forms from heat and pressure from tectonic plates, which create mountains, while rivers transport weathered rocks to lake beds, forming sedimentary rock as layers accumulate.

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Charlotte and Mia are studying why earthquakes are common in California. They learn that California sits at the border between two major tectonic plates: the Pacific plate, moving northwest, and the North American plate, moving southeast. Each year the California area has about 10,000 earthquakes. Which of the following describes why earthquakes are a common occurrence in California?

• The movement of the Pacific and North American plates against each other causes stress to build up, leading to earthquakes.

• The Pacific plate is moving faster than the North American plate, causing frequent volcanic eruptions.

• The North American plate is sinking beneath the Pacific plate, causing frequent landslides.

• The Pacific plate is stationary while the North American plate moves, causing the ground to shake.

Answer explanation

The correct choice explains that the movement of the Pacific and North American plates against each other builds up stress, which is released as earthquakes, making them common in California.

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Elijah and Mia are studying plate tectonics and learn that the two plates form a transform boundary because earthquakes are caused by plates sliding past each other.

• The two plates form a transform boundary because earthquakes are caused by plates sliding past each other.

• The two plates form a convergent boundary because earthquakes are caused by plates sliding past each other.

• The two plates form a transform boundary because earthquakes are caused by the Pacific plate subducting under the North American plate.

• The two plates form a convergent boundary because earthquakes are caused by the Pacific plate subducting under the North American plate.

Answer explanation

The correct choice states that the two plates form a transform boundary because earthquakes occur when plates slide past each other. This accurately describes the nature of transform boundaries, unlike the other options.

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NGSS.MS-ESS2-3

During a geology class, Arjun and Luna were discussing Earth's layers. Which of Earth's layers would they describe as being rocky and having the lowest density?

• crust

• mantle

• inner core

• outer core

Answer explanation

The crust is the outermost layer of Earth, characterized by its rocky composition and the lowest density compared to the mantle, inner core, and outer core, which are denser and composed of different materials.

During a geography class, Arjun and Rohan were discussing the formation of the Andes Mountains, which are the world's longest range of mountains running north to south along the Pacific Ring of Fire. They learned that it is known for its several volcanoes, including the world’s highest active volcano, Nevados Ojos del Salado. How are volcanoes like this formed?

• Divergent plate boundaries cause mountains to separate, leaving room for the convecting magma below to enter.

• Divergent plate boundaries cause plates to collide, causing subduction where convection in the mantle forces magma to the surface.

• Convergent plate boundaries carve out an opening at the top of the mountains, which allows convecting magma in the ground to rise.

• Convergent plate boundaries cause plates to collide. Oftentimes, this collision forces the denser plate to subduct while convection in the mantle forces magma to the surface.

Answer explanation

Volcanoes like Nevados Ojos del Salado are formed at convergent plate boundaries where one plate subducts beneath another. This subduction leads to melting and magma rising to the surface, creating volcanoes.

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Mia is studying how heat and the movement of Earth's tectonic plates contribute to the formation of an ocean basin. Which option best describes this process?

• Heat from the mantle conducts through tectonic plates causing them to melt.

• Heat from the mantle forms convection currents causing the plates to transform.

• Heat from the mantle forms convection currents causing the tectonic plates to diverge.

• Heat from the mantle conducts through the tectonic plates causing the plates to converge.

Answer explanation

Heat from the mantle creates convection currents that drive the movement of tectonic plates. This process causes the plates to diverge, leading to the formation of ocean basins as new oceanic crust is generated.

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During a science class, Benjamin and Priya learned that heat generated by the Earth's core is passed to the mantle by conduction. Which option below best describes how the flow of heat through the mantle affects the movement of the Earth's tectonic plates?

• Heated material in the mantle rises towards the crust through convection which causes plate motion.

• Heat conducted from the Earth's mantle moves tectonic plates due to the gravitational pull from the Earth's core.

• Heat is transferred from the mantle to the crust by radiation, which then causes the plates to move on the surface.

• Heated material in the mantle rises to the surface by radiation, which causes the crust to harden and move the plates.

Answer explanation

The correct choice explains that heated material in the mantle rises through convection, which drives the movement of tectonic plates. This process is essential for plate tectonics, unlike the other options that misrepresent heat transfer methods.

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Abigail and Grace are studying two tectonic plates. When they analyzed the data, they noticed that the two plates have been pushing against each other over the past ten years. What option below describes what will most likely occur between the two plates?

• The plates will slowly subduct causing an earthquake.

• The plates will quickly diverge forming an ocean basin.

• The plates will slowly converge causing a mountain to form.

• The plates will quickly transform causing the formation of a canyon.

Answer explanation

The two tectonic plates pushing against each other indicates a convergent boundary. Over time, this can lead to the formation of mountains as the plates slowly converge, making this the most likely outcome.

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NGSS.MS-ESS2-3

During a classroom discussion, Arjun asked, "How does the thickness of Earth's inner core compare to the mantle?"

• The inner core is thinner than the mantle.

• The inner core is less dense than the mantle.

• The inner core is a liquid and the mantle is a solid.

• The inner core is closer to the crust than the mantle.

Answer explanation

The inner core is indeed thinner than the mantle. The mantle is much thicker, comprising a significant portion of Earth's interior, while the inner core, although solid, is relatively small in comparison.