Earth's Changing Surface — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which type of plate boundary is MOST likely to build a tall mountain range on a continent?
A) Two plates pushing together
B) Two plates pulling apart
C) Two plates sliding past each other
D) Two plates standing perfectly still
Continent-to-continent collisions, like India hitting Asia, build huge mountain ranges such as the Himalayas.
2. Why are scientists confident that Earth's surface has changed over time?
A) They find ocean fossils on mountaintops
B) Mountains are always perfectly smooth
C) Rocks never change once they form
D) Rivers only flow uphill
Marine fossils high on mountains show the rock formed underwater, then plates lifted it up over millions of years.
3. Which list shows ONLY fast changes to Earth's surface?
A) Earthquake, volcanic eruption, landslide
B) Weathering, erosion, deposition
C) Glacier, fossil, canyon
D) Sediment, delta, rock layer
Earthquakes, eruptions, and landslides reshape land quickly, unlike weathering and erosion, which are slow.
4. Two plates pull apart under the ocean. What is MOST likely to form there?
A) A mid-ocean ridge with new rock
B) A tall fold mountain on land
C) A canyon carved by a river
D) A glacier sliding down a hill
At mid-ocean ridges, magma rises between separating plates and cools, creating new ocean floor over time.
Part B: Fill in the Blank
Write the correct answer on each line.
1. When one ocean plate slides beneath another plate, the process is called subduction.
Subduction at converging boundaries causes deep trenches, strong earthquakes, and chains of volcanoes.
2. The Ring of Fire is a zone around the Pacific Ocean famous for many volcanoes and earthquakes.
The Ring of Fire is dotted with volcanoes because it sits along many active plate boundaries.
3. Layers of rock that have been bent or wrinkled by plate pushing are said to be folded.
Folded layers are evidence that the rock was squeezed slowly while it was deep and warm.
4. A scientist who studies how plates move and shape Earth is studying plate tectonics.
Plate tectonics is the big-picture theory in Grade 4 that explains many slow and fast Earth changes.
5. Volcanic islands like Hawaii are built when lava cools and hardens above a hot spot in the mantle.
Hot spots are stationary plumes of hot rock that build island chains as plates move slowly over them.