Final Exam Review

A group of students observe igneous rocks. Some of the rocks have small, fine grains while other rocks have large coarse grains. Which statement would MOST LIKELY explain this difference?

• Some rocks were exposed to weathering.
• Some rocks cooled faster than other rocks when they formed.
  
• The rocks with larger grains were formed from larger sediments. 
• The rocks with larger grains experienced less pressure during formation. 

A group of students visited a farm. The farmland had a gentle slope to it. The farmer had straight rows of cotton planted. As he showed the students the crops, he explained that he was concerned about the amount of soil erosion he was experiencing due to runoff. After returning to school, the class discussed ways to prevent erosion.

Which method would MOST LIKELY prevent the MOST soil erosion due to runoff? 

• Use crop rotation
  
• Plant a wind break
  
• Reestablish forest cover 
• Practice contour farming 

Students are studying fossils found in different layers of a cliff. The teacher explains that the fossils formed over long periods of time. The fossils found in the upper layers of the cliff show desert plants that hold and retain water. The fossils in the lower layers of the cliff show many tropical rainforest plants such as ferns.

Which conclusion MOST LIKELY explains these differences? 

• The climate in the location was drier during later time periods. 
• The climate in the location was colder during later time periods. 
• There was an increasing number of animals bringing new plants into the location during later time periods. 
• There was an increasing number of plant-eating animals in the location during later time periods. 

In the early 1900s, a German scientist named Alfred Wegener hypothesized that the continents move on Earth’s surface. However, he never determined the mechanism by which this movement happens, and his hypothesis was not widely accepted. Later in the 20th century, other scientists determined that the ocean floor moves away from a mid-ocean ridge as magma rises through the rift. This magma solidifies to become new lithosphere.

How did this later discovery support Wegener’s hypothesis? 

• It showed that rifts are responsible for continental movement.
  
• It showed that if the ocean floor moved, so could other land masses.
  
• It showed that the continents were moving away from mid-ocean ridges.
  
• It showed that mountain building, volcanoes, and earthquakes occur underneath the ocean. 

A group of students create different models showing the movement of lithospheric plates. One student creates this model.

What will MOST LIKELY be created if this movement continues? 

• Fault
• Trench
• Rift Valley
• River Plain

On a trip to a river, a student found a rock. When she observed the rock more closely, she saw small particles, some shell fossils, and large particles.

What conclusion can she make about the rock with this information?

• The fossils mean this is most likely a sedimentary rock.
  
• The particle size means this is most likely an igneous rock.
  
• More information is needed because the rock could be either igneous or metamorphic. 
• More information is needed because the rock could be either metamorphic or sedimentary. 

A class looks at a sandstone sample from a cliff near a river. The students identify it as a sedimentary rock. Then they discuss what happened to the rock during the rock cycle. 
Student 1: As hot, liquid rock cooled, it created new crystals. The temperature of the liquid rock determined the size of the minerals.
Student 2: Preexisting minerals that became unstable in high heat and pressure changed into new minerals to form the sandstone.
Student 3: Deep underground, the existing minerals crystalized and grew larger.

Student 4: Pieces of sand accumulated over time. The sand was buried under more layers and eventually compressed into a solid rock. 

• Student 1
• Student 2
• Student 3
• Student 4