Exploring Earth's Dynamic Processes

At a **convergent plate boundary**, two plates move toward each other. What is most likely to form when an oceanic plate collides with a continental plate?

• A mid-ocean ridge

• A rift valley

• A subduction zone and volcanic mountain range

• A transform fault

At a **divergent plate boundary**, two plates move apart from each other. Which of the following best describes what happens at this type of boundary?

• One plate slides under the other, forming a trench

• New crust is formed as magma rises to fill the gap between the plates

• The plates grind past each other, causing frequent earthquakes

• Mountains are formed due to compression of the crust

A **transform plate boundary** is where two plates slide horizontally past each other. Which of the following is the most likely result of movement at a transform boundary?

• Formation of new ocean floor

• Creation of deep ocean trenches

• Frequent earthquakes along the fault line

• Formation of volcanic island chains

Earthquakes occur when energy is released along a **fault**. What causes the ground to shake during an earthquake?

• Hot magma pushing up through the crust

• Seismic waves traveling through Earth's layers after rocks suddenly slip

• Water rushing underground through caves

• Wind pressure building up beneath the surface

Earthquakes are most commonly found near **plate boundaries**. Why are plate boundaries more likely to produce earthquakes than the middle of a plate?

• Plate boundaries have more water, which causes shaking

• The middle of plates is too hot for earthquakes to occur

• Stress and friction build up where plates interact, causing rocks to break and slip

• Plate boundaries receive more sunlight, heating the rock

A **shield volcano** has gently sloping sides and produces runny lava. A **composite volcano** has steep sides and produces explosive eruptions. Based on this information, which type of volcano would be more dangerous to nearby communities and why?

• Shield volcano, because its lava flows faster and covers more area

• Composite volcano, because its explosive eruptions can send ash and debris over large distances

• Shield volcano, because it erupts more frequently

• Composite volcano, because it is always located near the ocean

**Magma** is molten rock found beneath Earth's surface, while **lava** is molten rock that has reached the surface. Which of the following correctly applies this concept?

• Lava is found in the mantle, and magma flows down a volcano's slope

• Magma is stored in a magma chamber underground, and it becomes lava when it erupts from a volcano

• Magma and lava are the same thing and can be used interchangeably

• Lava is hotter than magma because it is exposed to sunlight

**Erosion** is the process by which weathered material is carried away by agents such as water, wind, or ice. Which of the following is an example of erosion affecting a landscape?

• A rock cracking due to repeated freezing and thawing of water inside it

• A river carrying sediment downstream and depositing it at its mouth

• Acid rain chemically breaking down the minerals in limestone

• Tree roots slowly breaking apart a boulder

A farmer notices that the topsoil on a hillside is being washed away by rain. Which of the following actions would **best reduce** the effects of erosion on the hillside?

• Removing all plants and trees from the hillside

• Planting grass and trees to hold the soil in place with their roots

• Adding more water to the hillside to compact the soil

• Breaking up the soil into smaller pieces to allow better drainage

Over time, a river cuts through rock and forms a **canyon**. Which agent of erosion is responsible for this process, and how does it work?

• Wind carries sand particles that slowly grind away the rock

• Glaciers push rock aside as they move through the landscape

• Flowing water carries sediment that scrapes and wears away the rock over time

• Chemical reactions dissolve the rock instantly during rainstorms