Grade 7 Restless Earth worksheet
from Gradelings · Name: ______________________
How to explain it
- Earth’s layers from the outside in: crust, mantle, outer core, inner core.
- Earth’s crust is broken into plates that move slowly. Earthquakes and volcanoes happen mostly where plates meet.
- In undisturbed rock layers, the lowest layers and their fossils are the oldest.
Example: Which is older: a fossil in a deep layer or one in a layer above it? Layers settle one on top of another. The lower layer formed first. Answer: the fossil in the deeper layer
Question 1
Put these events in Earth's history in order, oldest first.
- 🧍Modern humans appear in Africa
- 🦠First simple life appears in the oceans
- 🐟First fish swim in the oceans
- 🦕First dinosaurs appear
First simple life appears in the oceans → First fish swim in the oceans → First dinosaurs appear → Modern humans appear in Africa
Hint: First simple life appears in the oceans: at least 3.5 billion years ago. First fish swim in the oceans: about 500 million years ago. First dinosaurs appear: about 230 million years ago. Modern humans appear in Africa: about 300,000 years ago.
Question 2
A tectonic plate moves about 5 cm per year (about as fast as fingernails grow). How far would it move in 100 years?
🌋5 cm per yearanswer boxcm
500 cm
Hint: Multiply the distance per year by the number of years: 5 × 100.
Question 3
What is a fossil?
🦴- A layer of soil on a farm
- A type of volcanic rock
- The preserved remains or traces of an organism from long ago
- A crystal that grows in caves
The preserved remains or traces of an organism from long ago
Hint: Bones, shells, footprints and leaf prints preserved in rock are all fossils.
Question 4
Many earthquakes and volcanoes happen around the edge of the Pacific Ocean. What is this zone called?
🌋- the Mid-Atlantic Ridge
- Pangaea
- the Ring of Fire
- the Equator
the Ring of Fire
Hint: Plates meet all around the Pacific, making a ring of volcanoes and earthquake zones.
Question 5
Which layer of Earth is made of liquid metal?
- the crust
- the outer core
- the mantle
- the inner core
the outer core
Hint: The outer core is liquid iron and nickel. Its swirling motion creates Earth's magnetic field.
Question 6
What was Pangaea?
- An ancient ocean that dried up last century
- A supercontinent that slowly broke apart into today's continents
- The first volcano on Earth
- A layer of Earth's core
A supercontinent that slowly broke apart into today's continents
Hint: Hundreds of millions of years ago, most land was joined in one giant continent.
Question 7
Which fossil is probably the oldest?
Fossils in undisturbed rock layers at a cliff Layer Fossil found 1 (top) mammoth tooth 2 dinosaur bone 3 ammonite shell 4 (bottom) trilobite - dinosaur bone
- ammonite shell
- trilobite
- mammoth tooth
trilobite
Hint: Rock layers form on top of each other, so in undisturbed rock the bottom layer is oldest and the top layer is youngest. This is called the law of superposition.
Question 8
The inner core is hotter than the surface of the Sun. Why is it solid?
- The enormous pressure squeezes it into a solid
- It is made of ice
- It is cooled by the oceans
- It gets no heat from anywhere
The enormous pressure squeezes it into a solid
Hint: The weight of all the rock above presses so hard that the iron can't melt.
Question 9
Put Earth's layers in order, from the surface to the centre.
- 🟠mantle (hot rock that flows very slowly)
- ⚪inner core (solid iron and nickel)
- 🌍crust (thin, rocky outer layer)
- 🔴outer core (liquid iron and nickel)
crust (thin, rocky outer layer) → mantle (hot rock that flows very slowly) → outer core (liquid iron and nickel) → inner core (solid iron and nickel)
Hint: The thin rocky crust is on top, then the thick mantle, then the liquid outer core and the solid inner core.
Question 10
What causes most earthquakes?
- Strong winds blowing over mountains
- Plates suddenly slipping along a fault
- Underground rivers freezing
- The Moon pulling on rocks every night
Plates suddenly slipping along a fault
Hint: Stress builds up where plates meet. When the rocks finally slip, the energy is released as shaking.
Answer key
- 1. First simple life appears in the oceans → First fish swim in the oceans → First dinosaurs appear → Modern humans appear in Africa
- 2. 500 cm
- 3. The preserved remains or traces of an organism from long ago
- 4. the Ring of Fire
- 5. the outer core
- 6. A supercontinent that slowly broke apart into today's continents
- 7. trilobite
- 8. The enormous pressure squeezes it into a solid
- 9. crust (thin, rocky outer layer) → mantle (hot rock that flows very slowly) → outer core (liquid iron and nickel) → inner core (solid iron and nickel)
- 10. Plates suddenly slipping along a fault
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