Origin of the Geosphere - Science 10 Geology

**Origin of the Geosphere** **History of the Earth** **What is the Geosphere?** **The geosphere** is the **Earth** itself. Early Earth was very hot Segregation by density (**Differentiation)** - Allowed heavy metals to sink while lighter materials "floated" Early earth started as a dust bal...

**Origin of the Geosphere** **History of the Earth** **What is the Geosphere?** **The geosphere** is the **Earth** itself. Early Earth was very hot Segregation by density (**Differentiation)** - Allowed heavy metals to sink while lighter materials "floated" Early earth started as a dust ball from nebular gas and dust brought together by **accretion.** **Accretion** the process in which dust clump together by static electricity to form larger and larger objects with the aide of gravity. **Velocity** -- too fast, collide with another body **Distance from the sun** -- Closer to the sun means less materials available **Mass** -- Mass increases, stronger gravitational pull **The Planets** **Inner Planets --** Mercury, Venus, Earth, Mars **Outer Planets** -- Jupiter, Saturn, Uranus, Neptune - Methane and Ammonia are the most common compounds **Vital Stats of the Earth** Earth is dominantly composed of 4 major elements: **Oxygen, Silicone, Aluminum, Iron** Earth is the only planet with water on its surface Earth is 4.54 billion years old **Shape**: Oblate spheroid (not perfectly spherical, not flat); has bumps, makes of spheroid **Axial Tilt:** currently at 23.5 degrees (changes between 22 to 24.5 degrees) - Areas near the equator receive more of the sun's energy. **Differentiation** The organization of the Earth's layers Less dense material rose and heavier material sank - Core: Iron - Crust: Basaltic or Granitic - Atmosphere **Earth's Layers** **Crust** - Outermost and thinnest layer - Continental (Granitic) - Oceanic (Basaltic) **Mantle --** Mainly composed of Peridotite **Outer Core --** The only liquid layer **Inner Core** -- Solid sphere - **Magnetosphere** The pressure experienced by the inner core is greater than the pressure experienced by the outer core, hence it maintains as a solid sphere. A diagram of the earth with Crust in the background Description automatically generated **Continental Drift Theory** At one point in time, all of the continents were joined together as one large mass of land, then the land spread apart and drifted into their current positions. Alfred L. Wegener Suggests that all continents were joined into a single land mass **Pangaea** (all land) and **Panthalassa**  **Evidences of C.D.T.** **Jigsaw Fit of Continents:** Coastlines of some continents fit together like a puzzle **Spread of Index Fossils:** Some fossils observed in continents separated by vast oceans. **Similar Lithologies across continents** - "Lithologies": physical characteristics of rock, including color, composition, and texture - Rocks and geologic structures in one continent match rocks found in the matching continent **Paleoclimate** - Materials observed in today's glaciers - Tropical fossils were observed in frozen regions. **Seafloor Spreading** A geologic process in which tectonic plates -- large slabs of earth's lithosphere -- split apart from each other Idea that oceanic crust is formed along mid-ocean ridges By Harry Hammond Hess. Hass envisaged that oceans grew from their centres, with molten material (basalt) oozing up from the Earth's mantle along the mid ocean ridges. This created new seafloor which then spread away in both directions.  **Red to orange:** Rock is between 0 to 40 million years old. **Green to purple:** Rock is between 100 to 200 million years old. **Paleomagnetism** Refers to the study of the ancient magnetism of rocks, specifically their location relative to the ancient North Pole and other rocks, through analysis of the permanent magnetism of ferromagnetic materials - Remanent Magnetism: permanent magnetism in rocks, resulting from the orientation of the Earth's magnetic field at the time of rock formation in a past geological age. - Geodynamo: the mechanism responsible for the generation of the Earth's magnetic field caused by the convection and conduction currents in the fluid core. - Rocks with magnetic minerals such as magnetite (Fe3O4) At temperatures above Curie temperature, they are randomly oriented. At temperatures below Curie temperature, they align themselves to the current magnetic field. *Curie temperature:  the **Curie temperature** (T~C~), or **Curie point**, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism.* Diagram of a diagram showing the different types of field directions Description automatically generated with medium confidence  Rocks with increasing age, point to pole locations far from the magnetic pole. This suggests: a. Earth had more than 1 magnetic pole b. The different continents moved **Apparent Polar Wandering Path** A map of the earth with directions Description automatically generated **Plate Tectonics** **Theory** dealing with the **dynamics** of the Earth's outer shell -- the lithosphere -- that revolutionized Earth sciences by providing a uniform context for understanding mountain -- building processes, volcanoes, and earthquakes. Explains how major landforms are created as a result of Earth's subterranean processes. Dynamics of the Earth's outer shell. **Types of Plate Tectonics** **Divergent Boundary:** occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common, and magma rises from the Earth's mantle to the surface, solidifying to create new oceanic crust. - Oceanic ridges: topographic expression of linear or curvilinear zones along which the Earth's oceanic crust is created or modified. They are found in every ocean basin and appear to girdle the Earth. - Rift Zones: areas where the volcano is rifting or splitting apart. - Materials erupted are always **basaltic** (rich in Si and Mg)  **Convergent Boundary** When two plates come together, it is known as a convergent boundary. The impact of the colliding plates can cause the edges of one or both plates to buckle up into mountain ranges or one of the plates may bend down into a deep seafloor trench. - Trenches, volcanos, mountains form - **Subduction --** where tectonic plates converge, the one with thin oceanic crust subducts beneath the one capped by thick continental crust. - when an oceanic plate meets a continental plate and slides beneath it. - **Subduction Zone:** consists of material scraped off the ocean floor near the coast (accretionary wedge) and a chain of volcanoes farther inland (volcanic arc) - **Opeoceanic/Continental:** Oceanic subducts beneath the continental plate. Volcanic Arc  - **Oceanic/Oceanic:** Older plated will subduct the younger plate. Island Arc. A volcanic arc is a chain of volcanoes, hundreds to thousands of miles long, that forms above a subduction zone. An island volcanic arc forms in an ocean basin via ocean-ocean subduction. The Aleutian Islands off the coast of Alaska and the Lesser Antilles south of Puerto Rico are examples. - **Continental/Continental:** Neither subducts the other. Mountains. **Transform Fault** - Two tectonic plates move past one another. - Changes the face of the landform.  **Philippine Geology** Philippines sits on a complex network of tectonic plate boundaries Philippine Mobile Belt (PMB) - Moved from somewhere in Indonesia to upwards. Palawan broke from Mainland Asia (China). That's why Palawan sits on different plate from the rest of the Philippines.