3 Types of Rocks and the Rock Cycle Igneous, Sedimentary, Metamorphic FreeSchool 1

Tsang Sau Hing Debbi

27 Aug 201603:12

Summary

TLDRThis educational video script delves into the fascinating world of geology, exploring the three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks, which make up 95% of the Earth's crust, form from cooling magma or lava, with examples like granite and obsidian. Sedimentary rocks, where fossils are often found, arise from layers of sediment such as sand and mud, with limestone, shale, and sandstone being common types. Metamorphic rocks undergo a transformation due to heat and pressure, changing from their original forms, such as shale turning into slate or limestone into marble.

Takeaways

🌋 Rocks are ubiquitous on Earth, varying in size, weight, and texture.
🔥 Igneous rocks are formed from cooling magma or lava, with intrusive types like granite forming beneath the Earth's surface and extrusive types like obsidian and pumice forming at the surface.
🏔️ Igneous rocks constitute approximately 95% of the Earth's crust.
🏞️ Sedimentary rocks are created from the accumulation of sediment layers, such as sand, mud, and organic material, which harden over time into rock, often preserving fossils.
🐚 Fossils are commonly found in sedimentary rocks due to the preservation of plant and animal remains within the sediment layers.
🗻 Examples of sedimentary rocks include limestone, shale, and sandstone.
⏳ Metamorphic rocks result from the transformation of existing rock types under extreme heat and pressure.
🌅 The change in rock types to metamorphic rocks can occur deep within the Earth or near the surface due to tectonic plate movements or magma.
💠 Different parent rocks give rise to distinct types of metamorphic rocks; for instance, shale becomes slate, sandstone becomes quartzite, and limestone becomes marble.
🌐 The three main types of rocks—igneous, sedimentary, and metamorphic—are integral to understanding Earth's geological processes.

Q & A

What are the three main types of rocks?
-The three main types of rocks are igneous, sedimentary, and metamorphic.
What does the term 'igneous' mean and how is it formed?
-The term 'igneous' means 'fiery' and it is formed when magma or lava cools, either slowly beneath the Earth's surface to form intrusive rocks like granite, or when lava cools on the surface during a volcanic eruption to form extrusive rocks.
What percentage of the Earth's crust is composed of igneous rocks?
-Igneous rocks make up about 95% of the Earth's crust.
How are sedimentary rocks formed?
-Sedimentary rocks are formed when sediment, which includes small particles of sand, mud, and organic material, accumulates over time in layers that become compressed and consolidated into rock.
In which type of rock can fossils commonly be found?
-Fossils can commonly be found in sedimentary rocks, as the process of forming these rocks can preserve plant and animal remains that are deposited into the sediment layers.
What is the meaning of the term 'metamorphic' and how are metamorphic rocks formed?
-The term 'metamorphic' means 'changed form' and metamorphic rocks are formed when existing rocks, such as sedimentary or igneous, are altered by extreme heat and pressure, either deep within the Earth or near the surface due to tectonic plate movement or magma.
What happens to shale when it is exposed to heat and pressure to form a metamorphic rock?
-When shale is exposed to heat and pressure, it becomes a metamorphic rock known as slate.
How does sandstone transform into a different type of rock under metamorphic conditions?
-Under metamorphic conditions, sandstone is transformed into quartzite.
What type of metamorphic rock is formed from limestone when it undergoes heat and pressure?
-Limestone becomes marble when it is subjected to heat and pressure.
Why are igneous rocks important in the Earth's crust?
-Igneous rocks are important because they make up a significant portion of the Earth's crust, and they can be the source of many valuable minerals and rocks used in construction and other industries.
How do the processes of erosion and deposition contribute to the formation of sedimentary rocks?
-Erosion breaks down rocks into smaller particles, and deposition occurs when these particles settle and accumulate in layers, eventually leading to the formation of sedimentary rocks through compaction and cementation.

Outlines

00:00

🌋 Types of Rocks and Their Formation

This paragraph introduces the three main types of rocks found on Earth: igneous, sedimentary, and metamorphic. Igneous rocks are formed from cooling magma or lava, with intrusive igneous rocks like granite forming slowly beneath the Earth's surface, and extrusive igneous rocks like obsidian and pumice forming when lava cools quickly at the surface during volcanic eruptions. Sedimentary rocks are formed from the accumulation of sediment such as sand, mud, and organic material over time, often in bodies of water like lakes or oceans. These sediments form layers that eventually consolidate into rock, and they can preserve fossils due to the preservation of plant and animal remains within the sediment layers. Examples of sedimentary rocks include limestone, shale, and sandstone. Metamorphic rocks are formed when existing rocks are changed by extreme heat and pressure, either deep within the Earth or near the surface due to tectonic plate movement or magma. Different parent rocks transform into specific types of metamorphic rocks; for instance, shale becomes slate, sandstone becomes quartzite, and limestone becomes marble.

Mindmap

Keywords

💡Igneous rock

Igneous rock, derived from the word 'igneous' meaning fiery, is formed from the cooling and solidification of magma or lava. In the video, it is mentioned that igneous rocks can be either intrusive, like granite, which forms when magma cools slowly beneath the Earth's surface, or extrusive, such as basalt and obsidian, which form when lava cools rapidly at the surface during volcanic eruptions. These rocks make up approximately 95% of the Earth's crust, highlighting their prevalence and importance in the Earth's geology.

💡Sedimentary rock

Sedimentary rock is formed from the accumulation of sediment, which includes small particles like sand, mud, and organic material. Over time, these particles settle and become compacted into layers, eventually solidifying into rock. The video emphasizes that sedimentary rocks often contain fossils, as the process of their formation can preserve the remains of plants and animals that were deposited into the sediment. Examples given in the script include limestone, shale, and sandstone, which are all significant for their role in recording Earth's history and the presence of ancient life.

💡Metamorphic rock

Metamorphic rock is the result of a transformation of existing rock types due to extreme heat and pressure. The term 'metamorphic' comes from the Greek for 'change form', and as described in the video, rocks such as sedimentary, igneous, or even other metamorphic rocks can undergo this change. This process can occur deep within the Earth where high pressures and temperatures exist, or near the surface due to tectonic plate movements or magma intrusion. The video provides examples of how different parent rocks transform into metamorphic rocks, such as shale becoming slate, sandstone becoming quartzite, and limestone becoming marble.

💡Magma

Magma is molten rock material found beneath the Earth's surface. It plays a crucial role in the formation of igneous rocks, as explained in the video. When magma cools slowly beneath the surface, it forms intrusive igneous rocks like granite. Magma's movement and cooling processes are key to understanding the geological activity that shapes the Earth's crust.

💡Lava

Lava is the term used for magma when it reaches the Earth's surface. As described in the video, lava cools rapidly to form extrusive igneous rocks. The cooling process of lava can result in rocks like basalt and obsidian, which are significant for their unique properties and the way they contribute to the geological record.

💡Intrusive

Intrusive refers to the process by which magma cools and solidifies beneath the Earth's surface, leading to the formation of igneous rocks. The video explains that intrusive rocks like granite are formed slowly over time, which allows for the development of large crystals and a coarse-grained texture.

💡Extrusive

Extrusive describes the rapid cooling of lava at the Earth's surface, resulting in the formation of igneous rocks with fine-grained or glassy textures. The video mentions extrusive rocks such as basalt and obsidian, which are important for understanding volcanic activity and the types of rocks produced by such events.

💡Sediment

Sediment is the collective term for small particles like sand, mud, and organic material that accumulate and eventually form sedimentary rocks. The video explains that sedimentary rocks are formed from layers of sediment that become compacted and solidified over time, often preserving fossils and providing a record of Earth's biological and geological history.

💡Fossils

Fossils are the preserved remains or traces of ancient life forms, often found within sedimentary rocks. The video highlights the significance of fossils in understanding the history of life on Earth, as they can be preserved within the layers of sediment that eventually form sedimentary rocks.

💡Consolidate

Consolidation is the process by which loose sediment becomes a solid sedimentary rock through compaction and cementation. The video mentions this process in the context of sedimentary rock formation, where layers of sediment are squeezed and compressed over time, leading to the formation of solid rock.

💡Tectonic plates

Tectonic plates are large slabs of the Earth's crust that move over the mantle. The video discusses how the movement of these plates can generate heat and pressure, contributing to the formation of metamorphic rocks. This geological process is essential for understanding the dynamic nature of the Earth's crust and the creation of various rock types.

Highlights

Rocks are found in various forms all over the planet.

There are three main types of rocks: igneous, sedimentary, and metamorphic.

Igneous rock is formed when magma or lava cools.

Intrusive igneous rock, like Granite, forms when magma cools slowly beneath the Earth's surface.

Extrusive igneous rock forms when lava cools during volcanic eruptions.

Examples of extrusive igneous rock include basalt, obsidian, and pumice.

Igneous rocks make up about 95% of the Earth's crust.

Sedimentary rock forms from the accumulation of sediment in layers over time.

Fossils may be found in sedimentary rocks due to the preservation of plant and animal remains.

Examples of sedimentary rock include limestone, shale, and sandstone.

Metamorphic rock is formed by the change in rock due to extreme heat and pressure.

Metamorphic rocks can be formed deep under the Earth or near the surface due to tectonic activity.

Different types of rocks become different metamorphic rocks when exposed to heat and pressure.

Shale becomes slate, sandstone becomes quartzite, and limestone becomes marble under metamorphic conditions.

Rocks can be classified by their size, weight, porosity, and density.

The process of rock formation involves cooling, compression, and transformation.

The Earth's crust is predominantly composed of igneous rocks.

Sedimentary rocks are significant for their potential to contain fossils.

Metamorphic rocks result from the alteration of existing rock types under specific geological conditions.