What is physical weathering? A Grade 6 science explanation.

📚 What is Physical Weathering?

Imagine you're building a sandcastle at the beach. The sun is hot, and the waves are crashing against it. Over time, the sandcastle starts to crumble and break apart, right? That's kind of what physical weathering does to rocks, but it happens over a much, much longer time!

Physical weathering is when big rocks are broken down into smaller pieces without changing what the rock is made of. It's like cutting a piece of paper – it's still paper, just in smaller pieces.

🧊 Types of Physical Weathering

• ❄️ Ice Wedging: Water gets into cracks in rocks, then freezes. When water freezes, it expands (gets bigger!). This expansion pushes the rocks apart, making the cracks bigger and bigger until the rock eventually breaks. Think of it like putting a water bottle in the freezer – it can explode if it's too full!
• ☀️ Thermal Expansion: Rocks get heated by the sun during the day and cooled down at night. This constant heating and cooling causes the rock to expand and contract. Over time, this stress can cause the rock to crack and break. Imagine bending a paperclip back and forth many times – it eventually breaks, right?
• 🌱 Plant Roots: Plant roots can grow into cracks in rocks. As the roots grow bigger, they push the rocks apart, causing them to break. It's like when a tree root cracks a sidewalk!
• 🌊 Abrasion: This happens when rocks are bumped and ground against each other by wind, water, or ice. Think of it like putting rocks in a tumbler – they get smoother and smaller over time.

⛰️ Why is Physical Weathering Important?

Physical weathering is super important because it helps create soil! Soil is what plants need to grow, and we need plants for food and oxygen. It also changes the landscape around us!

🧪 Physical vs. Chemical Weathering

It's important to remember that physical weathering is different from chemical weathering. Chemical weathering changes what the rock is made of, like when acid rain dissolves limestone. Physical weathering just breaks the rock into smaller pieces without changing its composition.

📝 Check Your Understanding

Can you think of other examples of physical weathering? What are some places where you might see it happening?

✅ Key takeaways

• 🔍 Physical weathering breaks rocks into smaller pieces.
• 💡 The rock's composition remains the same.
• 📝 Ice wedging, thermal expansion, plant roots, and abrasion are all types of physical weathering.