📖 Science Review
Estude cada tópico com atenção!
🌍 Earth Processes (WED)
🧠 Simple way to remember:
Weathering → breaks (quebra)
Erosion → moves (move)
Deposition → drops (deposita)
💥 Weathering
Weathering = Breaking down rocks into smaller pieces, called sediment. Happens slowly over time. The rock stays in place (no movement!).
🧊 1. Physical Weathering
Rocks break by physical forces
- Wind: Wears down rock surfaces
- Water: Washes and smooths rocks over time
- Temperature: Heating/cooling causes cracks (freeze-thaw: water seeps into cracks → freezes → expands → rock breaks)
🧪 2. Chemical Weathering
Rocks change through chemical reactions
- Chemical rain (acid rain): Dissolves minerals in rocks
- Rust (oxidation): Iron + oxygen + water → reddish color
- Water dissolving: Slowly dissolves limestone and soft rocks
🌳 3. Biological Weathering
Plants or animals break rocks
- Tree roots: Grow into cracks → push rocks apart
- Burrowing animals: Worms, rabbits dig into soil and rock
- Lichens and mosses: Produce acids that break down rock
🌊 Erosion
Erosion = Movement of materials: soil, sand, rocks. It happens AFTER weathering breaks rocks down.
💨 Caused by:
- Water: Rivers, streams, floods carry sediments. Rain washes soil away. Ocean waves crash against coastlines.
- Wind: Picks up loose particles (sand, dust). Abrasion: wind-carried particles crash into rocks.
- Ice/Glaciers: Huge masses of ice scrape and carry rocks. Very slow but very powerful!
🏖️ Deposition
Deposition = When materials are dropped in a new place. Happens after erosion.
🏝️ Examples of Deposition
- Sand dunes: Wind drops sand particles that build up
- Deltas: Rivers meet the ocean → deposit sediment
- Beaches: Sand deposited by waves and currents
- Floodplains: Sediment deposited when rivers overflow
⚖️ Weathering vs Erosion vs Deposition
| Process | What happens | Movement? | Example |
|---|---|---|---|
| Weathering | Rocks break into smaller pieces | NO | Freeze-thaw cracking a rock |
| Erosion | Broken pieces are carried away | YES (transport) | River carrying sand downstream |
| Deposition | Carried pieces are dropped | YES (settling) | Sand forming a dune |
🪨 Earth Materials
Examples of Earth Materials: rocks, sand, clay, soil, minerals
Each material has different uses:
🏗️ Uses of Earth Materials
| Material | Use |
|---|---|
| Clay | Making bricks |
| Sand | Making glass |
| Rocks | Construction |
| Coal | Energy (fuel) |
🪟 Glass (from Sand)
- Ingredients: Sand (silica/quartz) + soda ash + limestone
- Process: Heated to over 1,700°C → melted → shaped → cooled
- Types: Float glass (windows), tempered glass (phones, cars — 5x stronger), fiberglass, mirrors
- Recycling: Glass is highly recyclable — crushed and melted to make new products
⛏️ Coal (from Ancient Plants)
- Formation: Dead plants in ancient swamps → squashed under dirt and heat → millions of years
- Mining: Underground mining (tunnels) or Surface mining (scooping)
- Uses: Electricity (burned → steam → turbines), steel, cement
- Problem: Burning coal causes pollution
- Alternatives: Wind and solar power
🌿 Soil and Plants
🌱 Roots help:
- Hold soil together
- Reduce erosion
⚠️ Without plants:
- Soil becomes unstable
- Erosion increases
🌱 Human Actions and Their Impact
🚫 Harmful Actions → Negative Impact
Cutting down forests (deforestation)
- Animals lose their homes
- Less oxygen in the air
- More climate problems
Throwing trash in nature
- Pollution of land and oceans
- Animals can get sick or die
- Dirty environment for humans
Burning fossil fuels (cars, factories)
- Air pollution
- Global warming (Earth gets hotter)
- Health problems for people
Wasting water and electricity
- Natural resources run out faster
- Less water available for people and animals
Building in unstable areas
- Risk of landslides
- Soil erosion increases
✅ Beneficial Actions → Positive Impact
Planting trees
- Cleaner air
- Homes for animals
- Helps reduce global warming
Recycling and reusing materials
- Less waste in landfills
- Saves natural resources
Saving water and energy
- Resources last longer
- Protects the environment
Protecting animals and natural areas
- Balanced ecosystems
- Biodiversity is preserved
Building barriers
- Protects land from erosion
- Prevents flooding