Bio Notes: The Geosphere PDF

**Bio Notes: The Geosphere** **Materials in the geosphere:** A thin layer of soil covers much of earth's land, under that is a layer of broken rock and that is on top of a layer of mostly solid rocks surrounding a hot metallic center - The basic building materials for rocks soil and metals are...

**Bio Notes: The Geosphere** **Materials in the geosphere:** A thin layer of soil covers much of earth's land, under that is a layer of broken rock and that is on top of a layer of mostly solid rocks surrounding a hot metallic center - The basic building materials for rocks soil and metals are minerals, they combine in different ways **Minerals:** **Mineral properties:** They have physical properties such as: color, luster, streak **Luster:** the way a mineral's surface reflects light **Streak:** the color of a mineral's powder - Some minerals reflect a lot of light and others do not which makes them appear either shiny or dull There is also **Hardness, Cleavage and fracture:** They are other physical properties of minerals where: **Hardness:** how hard a mineral is; certain minerals are harder than others and "Mohs" scale is used to rank minerals from 1 to 10 based on their relative hardness, Talk is the softest mineral and diamond is the hardest mineral. **Cleavage:** the tendency of a mineral to break along a smooth flat surface. **Fracture:** the tendency of minerals to break along irregular surfaces. \*fun fact: a diamond can only be scratched by another diamond!\* **Rocks:** Rocks are naturally occurring slid comprised of minerals and other materials, scientists classify them based off of how they are generated. **There is 3 main types of rocks:** 1. Igneous 2. Metamorphic 3. Sedimentary **Igneous** rocks are formed when molten rock material cools and hardens which can happen deep inside the earth as magma cools or when molten material called lava flows onto earth's surface and cools **Metamorphic** rocks form when high temperatures and extreme pressures act on igneous, sedimentary and other metamorphic rocks, it alters its texture or its chemical composition and forms new metamorphic rocks **Sedimentary** rocks form when water, wind, ice or gravity erodes sediment and over time the weight from the upper layers of sediment compresses the lower layers, it compacts and cement together forming new sedimentary rocks (rock fragments call sediments form sedimentary rocks) **Soil:** **Soil** is the most important layer in the geosphere, it is the loose, weathered material in which plants grow. - At earth's surface, interactions between rocks, air, water and organisms form soil. \*\*IMPORTANT: Wastes from organisms add nutrients into soil\*\* **The 3 horizons:** **A horizon:** the layer that contains the most organic matter in the soil which also makes it usually the darkest layer **B horizon:** is formed when water from rain or snow seep through the first layer of soil's pores carrying clay particles, the clay particles then are deposited below the upper layer forming the B horizon, other materials also take place in forming the B horizon **C horizon:** the layer of weathered parent materials below the B horizon, parent materials can be rocks or sediments **Earth's layers:** Earth has three main layers; the curst, the mantle and the core. The densest layers is the core (inner core) and the least dense is the crust and the density of the thick mantle varies. **Upper mantle: solid, mg and fe silicates** **Lower mantle: solid, mg and fe silicates** **Outer core: liquid, fe** **Inner core: solid, fe** **The crust:** The thin outer layer of the geosphere and it has 2 types: oceanic and continental Oceanic crust is the one under the oceans and is denser Continental crust is the one that forms up the continents and is thicker \*\*the most common element found in the crust is oxygen followed by silicon\*\* **The mantle:** The thick rocky middle layer of the geosphere and it has the largest volume out of any of earth's layers **The lithosphere:** The crust and uppermost mantle form a brittle outer layer called the lithosphere **The asthenosphere:** this weak partially melted part of the mantle is called the asthenosphere **The core:** The dense metallic center of the earth, it is devided into 2 layers one is liquid and one is solid **Outer core:** due to the high temperatures near earth's center the outer layer of the core is liquid, as the earth spins on its axis the molten metal flows. **Inner core:** inside the outer core is a sphere of solid metal, temperatures in this inner core are extremely hot and can reach up to 4300 c, despite the scorching heat the metal inside it isn't molten. By : Jad Al Hussein.