Review the key ideas from the geology strand (Lessons 20-29), then test yourself with 10 multiple-choice questions and 3 short-answer questions.
Quick Review
Focus: Earth has four layers, the crust, mantle, outer core and inner core. Seismic waves reveal this hidden structure, and density increases from crust to core.
Key terms: Crust, Mantle, Outer core, Inner core, Seismic waves
Focus: Earth's crust is broken into plates that move on the mantle by convection. Wegener's continental drift evidence and seafloor spreading support the three boundary types.
Key terms: Continental drift, Convection, Plate boundary, Seafloor spreading
Focus: Earthquakes start at the focus underground and shake hardest at the epicentre above it. Magnitude is measured on a logarithmic scale, and surface waves cause the most damage.
Key terms: Focus, Epicentre, Seismic wave, Magnitude
Focus: Volcanoes form at divergent boundaries, subduction zones and hotspots. Silica content controls eruption style, giving shield, composite and other volcano types.
Key terms: Magma, Lava, Silica, Hotspot, Shield volcano, Composite volcano
Focus: The three rock types, igneous, sedimentary and metamorphic, form by different processes and change into one another over geological time. Only sedimentary rock contains fossils.
Key terms: Igneous, Sedimentary, Metamorphic, Rock cycle
Focus: Weathering breaks rock down in place (physical, chemical or biological); erosion then moves the pieces away by water, wind, ice or gravity. Deposition drops them in a new place.
Key terms: Weathering, Erosion, Deposition, Oxidation
Focus: Soil is weathered rock, organic matter and living organisms arranged in horizons (O, A, B, C, R). Australian soils are often old and nutrient-poor, and clearing vegetation can cause salinity.
Key terms: Soil horizon, Organic matter, Leaching, Salinity
Focus: Resources are renewable or non-renewable. Minerals and ores are dug from rock, while coal, oil and gas form over millions of years and so are non-renewable on human timescales.
Key terms: Renewable, Non-renewable, Mineral, Ore, Fossil fuel, Sustainability
Focus: Earth is about 4.6 billion years old. The geological timescale (eons, eras, periods) is built from rock layers, fossils and radiometric dating. Humans appear only at the very end.
Key terms: Geological timescale, Eon, Stratigraphy, Radiometric dating
Focus: Fossils form in several ways, and index fossils help date rock layers. The fossil record shows species change over time, and two great mass extinctions reshaped life on Earth.
Key terms: Fossil, Index fossil, Mass extinction, Transitional fossil
Multiple Choice (10 questions)
1. Which layer of the Earth is the only one that is liquid?
2. What drives the movement of Earth's tectonic plates?
3. Which observation was evidence for Wegener's idea of continental drift?
4. The point on Earth's surface directly above where an earthquake starts is called the:
5. What property of magma most controls whether a volcano erupts gently or explosively?
6. Which rock type forms when layers of sediment are compacted and cemented together?
7. What is the key difference between weathering and erosion?
8. Besides weathered rock and living organisms, what is the third main ingredient of soil?
9. Why are coal, oil and gas described as non-renewable resources?
10. Why are index fossils useful to geologists?
Short Answer (3 questions)
From the surface to the centre the four layers are the crust, the mantle, the outer core and the inner core (1 mark for correct order). The outer core is the only liquid layer; the inner core is solid because of the enormous pressure at the centre (1 mark).
Weathering is the breaking down of rock into smaller pieces in place, without the pieces being moved (1 mark). An example is water freezing in a crack and splitting the rock (physical weathering), or rainwater slowly dissolving limestone (chemical weathering) (1 mark). Erosion is the movement of those broken-down pieces away to a new place by an agent such as water, wind, ice or gravity (1 mark). An example is a river carrying sand and gravel downstream.
Fossils are found in sedimentary rock layers, and deeper layers are older than the layers above them (1 mark). When fossils from many sites are compared, they show a clear pattern: simpler life forms appear in older rocks and more complex, modern forms appear in younger rocks, and transitional fossils (such as Archaeopteryx or Tiktaalik) show in-between features. This consistent, worldwide pattern is strong evidence that species have gradually changed over time (1 mark). One major mass extinction is the K-Pg extinction about 66 million years ago that wiped out the non-bird dinosaurs (accept the Permian-Triassic extinction about 252 million years ago) (1 mark).
Put what you have reviewed to the test! Jump through the checkpoint questions in game form.
Play GameTick the box when you have finished the questions and played the game.