Earth's Changing Surface — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A large sheet of slowly moving ice that can carve valleys is called a glacier.
Glaciers shape the land by scraping rock as they move and dropping sediment when they melt.
2. When a glacier melts and leaves behind piled-up rock and dirt, the pile is a moraine.
Moraines are evidence in Grade 4 science that glaciers once covered an area and dropped sediment as they retreated.
3. Most layers of sedimentary rock formed at the bottom of an ancient ocean.
Many flat rock layers are evidence that the area was once under a sea where sediment slowly piled up.
4. Footprints of dinosaurs preserved in rock are called trace fossils.
Trace fossils show behavior of ancient animals, while body fossils show what they looked like.
5. When the surface shakes because two plates suddenly slide past each other, the ground motion is an earthquake.
Earthquakes leave evidence such as cracks in rock layers and offset roads or fences.
6. Mountains that form when lava and ash pile up are called volcanic mountains.
Volcanic mountains, like the Cascades, are evidence of fast changes building new landforms.
7. Sand dunes are made when wind moves and drops grains of sand.
Wind erosion and deposition build dunes, showing how moving air reshapes Earth's surface in deserts and beaches.
8. When water freezes inside a crack in a rock, it pushes the rock apart. This is called ice wedging.
Ice wedging is a Grade 4 example of physical weathering that breaks rocks apart in cold places.
9. A river that slowly cuts deeper into the land creates a steep-sided valley called a canyon.
Canyons are direct evidence of long-term erosion by running water.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Moraine
→ Pile of rock and dirt left behind by a melted glacier
Mound of sand built up by blowing wind in a desert or beach
Sand dune
→ Mound of sand built up by blowing wind in a desert or beach
Footprint or burrow of an ancient animal preserved in rock
Ice wedging
→ Rock cracking when water freezes inside it and expands
Pile of rock and dirt left behind by a melted glacier
Trace fossil
→ Footprint or burrow of an ancient animal preserved in rock
Rock cracking when water freezes inside it and expands
Linking the term with its process helps students explain evidence of changing Earth in their own words.