Good day. Ever wondered where soil really comes from or how a mighty mountain slowly turns into sand? You're in the right place. Welcome to Magfar Online. Your gateway to expertly crafted content prepared by seasoned academics, meticulously arranged into playlists by grade and subject, unlocking value anytime, anywhere. And yes, even from the comfort of your couch. Today we are starting a series into an incredible natural phenomenon called weathering. Rocks that split like onions and ice cracking open mountains. Sound unbelievable? Well, stick around because today we're exploring all these astonishing processes, the concept of weathering and physical weathering. But first, let's start with a fun question. Where exactly does soil come from? Drop your best guess or most creative idea in the comments below. Who knows, you might just get a shout out. And hey, stay tuned until the end for some thoughtprovoking questions designed to challenge and boost your confidence. Think of it as your own miniquiz game without the scary teacher stare. Don't forget to like, subscribe, and click that bell icon because with Magfar Online, learning never stops. New weekly uploads await you, full of fascinating insights, helpful explanations, and maybe even a laugh or two. So, let's get started. [Music] As mentioned earlier, we are going to learn about a very important concept in geography called weathering. Weathering is the process that breaks down rocks and minerals on the earth's surface into smaller pieces in situ. It happens right where the rocks are found. This means the rocks are broken down in situ without being moved. Think of it like this. A large rock sits outside. Over time, wind, rain, temperature changes, and even living things like plants and animals cause the rock to weaken, crack, and eventually crumble into smaller pieces. This is what we mean by weathering. You can also think of weathering as the gradual breakdown of rocks into smaller pieces when they are exposed to natural elements like wind, water, heat, and cold. This process happens because of various natural forces such as flowing water, moving air, temperature changes, chemical reactions, and even the actions of plants and animals. One important thing to remember is that weathering is usually a slow and invisible process. You won't see rocks breaking apart quickly. It takes many years, even centuries, for noticeable changes to occur. Weathering is one of the key processes that shapes the landscape around us. It prepares material for erosion, but it is not erosion itself because erosion involves movement while weathering only involves breaking down. Weathering helps form soil, influences the shape of hills and valleys, and even exposes valuable minerals. There are three main types of weathering. physical or mechanical weathering, chemical weathering, and biological weathering. Today, we'll focus on physical weathering only. Check out the links below on chemical and biological weathering. [Music] Physical weathering, also known as mechanical weathering, is the type of weathering where rocks are broken down into smaller pieces without changing their chemical composition. In other words, the rock stays the same material. Only the size and shape of the rock changes. This type of weathering is mainly caused by physical forces such as temperature changes, water, wind, pressure, and the actions of plants or animals. Let's explore the main types of physical weathering so you can really understand how it works. One common type of physical weathering is called freeze thor and it is also known as frost wedging or frost shattering. This happens in places where temperatures repeatedly go above and below freezing. Water from rain or melted snow enters cracks and holes in rocks during the day when temperatures are high. At night, when the temperature drops below 0° C, the water freezes and turns into ice. Ice takes up more space than water, so it expands by 9% and puts pressure on the rock and wedge the rock apart. Over time, this repeated freezing and thoring causes the cracks to widen and eventually the rock breaks apart. After this process has happened many times, the rock can split in two. Each freeze thor cycle widens the cracks in the rock. Small rocks then fall down the side of the valley as scree. Freezethor weathering is driven by cold temperatures and repeated temperature changes. Another important type of physical weathering is exfoliation, also known as onion skin weathering. Exfoliation is the process where the outer layers of rock slowly peel away due to changes in temperature and pressure. This typically occurs in hot, dry regions where there are large differences between daytime and nighttime temperatures. During the day, the outer layers of the rock heat up and expand more quickly than the inner layers. At night, as temperatures drop, the outer layers cool and contract faster than the inner layers. This continuous cycle of uneven expansion and contraction creates stress within the rock. Over time, the outer layers crack and peel away similar to the layers of an onion. Hence the name onion weathering. Exfoliation occurs without chemical change in the rock making it a mechanical process. We also have pressure release or unloading which occurs when deep rocks are suddenly exposed to the surface. For example, after erosion removes the overlying material, these rocks were used to being under great pressure underground. When that pressure is removed, the rock expands and cracks form on the surface. This allows weathering to take place more easily. Salt crystal growth is another type of physical weathering, especially common in coastal or desert areas. In this process, salty water enters the pores or cracks in rocks. When the water evaporates, salt crystals are left behind. As these crystals grow, they exert pressure on the surrounding rock, eventually causing it to break apart. This process, known as salt wedging, is most common in dry climates like deserts. Abrasion is a key type of physical weathering that occurs when rocks are broken down through direct contact with other rocks or particles. This usually happens as rocks are moved by natural forces. The process is similar to how sandpaper smooths wood. Over time, the friction between rock surfaces causes small fragments to be chipped away, resulting in smoother and more rounded rocks. There are three main natural forces that drive abrasion. Moving water, wind, and gravity. Moving water, such as rivers, waves, or rain, carries rocks, sand, and pebbles that collide with one another and the riverbed, causing a grinding effect. This explains why river rocks are often smooth and rounded. They have been constantly araided by the water's movement. In dry sandy regions like deserts, wind abrasion occurs when sand particles are blown across rock surfaces. These particles act like tiny projectiles, gradually blasting and smoothing the rock. Over time, wind abrasion can sculpt rocks into unusual shapes. Gravity contributes to abrasion during events like landslides or rock falls. As rocks tumble down slopes, they collide and scrape against each other, breaking into smaller, more rounded pieces. Overall, abrasion is a mechanical process, meaning it alters the shape and texture of rocks without changing their chemical makeup. Over long periods, abrasion plays a major role in reshaping landscapes, particularly in environments with strong winds, flowing water, or frequent rock movement. As we wrap up today's exciting journey into physical weathering, remember it's all about the power of nature breaking rocks apart without changing their chemical makeup. Temperature swings, water freezing and thoring, pressure release, and salt crystals have all shown their amazing ability to shape our Earth's surface. Before you leave, let's test your knowledge. Pause the video and challenge yourself with the following quick questions. This practice will help reinforce everything we've learned today and increase your confidence. And guess what? Our adventure isn't over yet. Next time we will be looking into chemical weathering, where rocks don't just break, they transform. Curious about how something as strong as rock can literally change into something entirely new? Don't miss our next video. The link is right in the description below. Thanks for exploring with us today and we hope you enjoyed it. 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