Q1 GR10 Science Reviewer PDF

1 - THEORY OF PLATE TECTONICS AND FORMATION OF CONTINENTS Clarence Edward Dutton's Theories Raisin Theory - "according to this theory, the earth is like a grape that contracted into a raisin due to a cooling process that occurred on Earth after the big bang about 13.77 billion years ago." Scientists...

1 - THEORY OF PLATE TECTONICS AND FORMATION OF CONTINENTS Clarence Edward Dutton's Theories Raisin Theory - "according to this theory, the earth is like a grape that contracted into a raisin due to a cooling process that occurred on Earth after the big bang about 13.77 billion years ago." Scientists believe that the cooling process caused the contraction and pressure that allowed some parts of the crust to rise and form mountains, or depress downwards forming ocean basins and many more. The Theory of Isostasy (1889)- "the tendency of Earth's crust to attain equilibrium and distribution of the material in Earth's crust. Which states that the crust is floating on the mantle rather than resting on it— like a boat on water. - This theory is based on the opposing influence of buoyancy and gravity. TECTONIC - refers to the processes that result in the structure and properties of the Earth's crust and its development over time. - Refers to Tectonic Plates(lithospheric plates) which are massive slabs of solid rock that surround the earth's surface. - Generally composed of continental and oceanic lithosphere Tekton, meaning carpenter or builder Many scientists thought that the earth seemed too much like a jigsaw puzzle, with the coasts of South America and Africa fitting together. Abraham Ortelius - He considered the possibility of continents once being a huge land mass. Theatrum Orbis Terrarum is an atlas he published which is considered the first true modern atlas. He also published his observations titled "Thesaurus Geographicus" wherein he noted that the Americas were "torn away from Europe and Africa by earthquakes and floods." He followed up by saying "The vestiges(traces) of the rupture reveal themselves if someone brings forward a map of the world and carefully considers the coasts of the three continents." Which means the traces of cracks formed by earthquakes look obvious if someone carefully looks at the coasts of the Americas, Europe, and Africa. Georges-Louis Leclerc (1770) Also known as Count Buffon, ALSO commented that the continents of Africa and South America seemed to fit each other. He also supported the idea of Ortelius that earthquakes may have caused the separation of the two. Francois Paget (1666) A naturalist who commented about the origin of the Atlantic Ocean. He stated that an undivided continent existed before Noah’s Flood. However, a part of the continent sank leading to the formation of the Atlantic Ocean. WEGENER'S THEORY OF CONTINENTAL DRIFT A theory by German Climatologist Alfred Wegener presented in his book “The Origin of Continents and Ocean” in 1915 He expanded this theory and presented evidence that Pangaea(All-Earth) had really existed during the permian period. He explained that about 1.1 billion years ago, a supercontinent called Rodinia existed BEFORE pangaea. 1.1 Billion Years ago - A super continent called Rodinia existed before Pangaea 514 Million Years Ago - 425 Million Years Ago(Ma) - Laurasia began to slowly drift southward and it crashed into Gondwanaland a 100 million years later 356 Ma - A vast sea called Panthalassa formed surrounding Pangaea 251 - 65.5 Ma - Tethys Sea separated the two continents Laurasia and Gondwanaland During the late triassic period - Pangaea began to split into two smaller supercontinents, recreating Laurasia and Gondwanaland, which moved to the planet's northern and southern poles, respectively. (TO CLEAR THINGS UP, LAURASIA AND GONDWANALAND EXISTED BEFORE AND AFTER PANGAEA, MSG FOR FURTHER CLARIFICATION) Earth is generally composed of 58 crustal plates. Out of these plates, scientists have identified 15 major plates; seven or eight of which are primary plates and the others are smaller plates. SPECIAL NOTE, THE NAZCA PLATE IS CONSIDERED BOTH A PRIMARY AND SECONDARY PLATE. Primary Plates - African Plate - Eurasian Plate - Indo-australian Plate - North American Plate - Pacific Plate - South American Plate Secondary Plates - Arabian Plate - Caribbean Plate - Cocos Plate - Indian Plate - Juan de Fuca Plate  - Philippine Sea Plate Lithospheric Plates Continental Plate - Thick, less dense and older - About 25 miles (32 kms) thick - Mostly composed of GRANITE Oceanic Plate - Thin, dense - sinks under continental crust and younger - Is only about 3-5miles(8 kms) Thick - Mostly composed of BASALT Granite is a light-colored igneous rock with large grains. Granite is composed of quartz and feldspar, with minor amounts of mica, amphiboles, and other minerals. Basalt is a dark-colored, fine-grained, also igneous rock composed of plagioclase and pyroxene minerals. 2 - EVIDENCE OF PLATE MOVEMENT Certain land reptiles like Lystrosaurus and Cynognathus have fossils with striking similarity with ones on different continents which implies that the continents were connected as one. Antonio Snider Pellegrini, a French scientist, theorized that all continents were once connected during the Pennsylvanian Period but the “Great Flood” had separated them(314-280 Ma) Roberto Mantovani in 1889 proposed the same idea, although he thought that the reason was because of the Earth expanding due to heat and volcanic activity Eduard Suess, an Australian scientist, supports that theory. He states that the seeds of the fern Glossopteris are too large to be dispersed by wind, so their distribution can only be explained by continental drift 3 - PLATE BOUNDARY Seafloor Spreading Theory A theory proposed by Harry Hess, an American geologist, professor and military officer in the 1960s. - Implies that, as a result of volcanic activity, magma spreads apart the seafloor leading to the creation of ridges and a new crust. Tectonic Plate Boundaries Divergent - Plates move apart, resulting in the rise of material from the Mantle to fill in the gap and create a new seafloor. This is a linear feature that exists between two plates that are moving away from each other. Convergent  - Plates collide or smush into each other, causing one of the slabs to go under the other causing a process known as Subduction Subduction is a process where tectonic plates go under other plates into the earth's interior. Regions where this occurs are known as Subduction Zones The Wadati-Benioff zone is an area where earthquakes occur whenever and wherever subduction happens. Types of Convergent Boundaries 1. Oceanic-Continental - Oceanic plates subducting under a continental plate due to density and thickness difference. 2. Oceanic-Oceanic - Oceanic plates subducting under another oceanic plate. 3. Continental-Continental - The collision of continental plates smashing together to create mountains. Transform Fault/Boundary - Plates slide past each other(horizontally), without creating or destroying anything. Just shifting positions. Usually found on the seafloor, California’s San Andreas’ fault is an example of this. Rift Valley’s - Is a linear shaped lowland or ravine between several highlands or mountain ranges created by a geological rift or fault. - This is formed on a divergent boundary, a crustal extension or a surface spread. Types of Transform Boundaries 4 - MANTLE CONVECTION THEORY Arthur Holmes proposed this theory in 1929 based on Wegener’s observations. - Implies that the movement of our mantle layer pulls the lithosphere under and into the mantle in a conveyor belt-like motion due to convection. Slab Pull Theory - according to this theory, subduction is caused by gravitational forces pulling down the lithosphere rather than the mantle pulling it. It says that the older and denser slabs get affected more leading to them being pulled down the mantle and under the younger and lighter slabs. 5 - INTERNAL STRUCTURE OF THE EARTH Earth's layers Crust - the outermost layer and the top component of the lithosphere - the thinnest as it makes up only 1% of earth. - sits on the asthenosphere Mohorovicic Discontinuity - boundary between crust and mantle Mantle - made of molten rock - the largest and most massive layer of earth - has an average temperature of 3,700 Upper mantle - extends up to 660km and consists of peridotite and dunite which are solid, ultramafic rocks made up of olivine and pyroxene Lower mantle - under the upper mantle, extends to 2,200km Gutenberg Discontinuity - boundary between mantle and outer core Outer core - The only liquid layer, made up of iron and nickel - Responsible for earth's magnetic field - 5,000°C Lehmann Discontinuity - boundary between inner and outer core Inner core - Deepest and hottest layer, about 5k°C to 6k°C - Solid with a thickness of 1,250 km 5 - LANDFORMS These are natural physical features found on the earth’s surface. - Formed by natural forces such as: Water, wind, ice, and Earth’s tectonic plates. - Some landforms are formed in a single day, while others take millions of years to form. The topography of earth is made up of numerous landforms: Mountain ranges, Hills, Plains, and Plateaus are some of the most common. Aeolian Landforms - Created from the chemical and mechanical action of wind. - The term “Aeolian” comes from Aeolus, the Greek god of wind. 1. Dunes, mounds or small hills made of sand. Red. 1-10 m high May be dome, crescent, star, linear, or parabolic-shaped. The most common type of dune is the “Barchans” 2. Loess, silt-sized sediment created by the accumulation of dust. Yellow. Varies between a few cm to about 100m thick. Is a layer of fine, mineral-rich material. Is a result of glacial activity in an area. 3. Mushroom rock, Is a naturally occurring rock formed as a result of earthquakes or glacial action Erosional Landforms - Created from exclusively erosional and weathering activities. 1. Mesas, also called “tabletop mountains”, are elevated areas of land with a flat top and sides that are usually steep cliffs. They are usually surrounded by a resistant rock known as Cap Rock 2. Butte, same as a mesa with the only difference being, a butte covers a smaller area. They are formed by erosion when a hard cap rock overlies a layer of less resistant rock. 3. Canyon or gorge, is a deep ravine between cliffs that is often carved from the landscape by a river, wind , or glacier. It may appear like a valley except that it is deep-seated, narrow, and surrounded by steep sides. Unlike other landforms, this was formed by water and wind erosion over time. Mountainous and Glacial Landforms - Are those that rise higher than the rest of their surroundings. 1. Volcanoes are controlled by their creation process and continually act on them after their formation. A volcanic mountain can be identified by its vent 2. Hills are elevated pieces of land that are formed by faulting. Covered with grass and smaller than mountains, only about 300m high. Has sloped/curved sides. It is possible that Hills may come from mountains when extreme erosion occurs. 3. Valley or dale, is a low-lying area usually between hills or mountains. Formed by the actions of rivers and glaciers.  4. Glacial Landforms(GL) are the result of the actions of glaciers. - Glaciers are huge, slow-moving bodies of ice. Most of the GL’s we have today were created by the movement of large ice sheets during the quaternary glaciations. There are two main types of Glaciers Alpine Glaciers are formed in high mountains, while Continental Glaciers are formed in cold Polar Regions V Shaped = water U Shaped = glaciers Fluvial and Coastal Landforms - Those that underwent sedimentation, erosion, or deposition on the river bed. 1. Delta, a low-lying triangular area located where a river meets the ocean, seas, or estuaries. It contains rich soil which has been washed and scattered by running water. - Alluvium refers to the sediment that has accumulated due to the interaction with water. - Deltas were formed 7,000 years ago 2. Peninsula, also called byland or biland, is a piece of land connected to the mainland by an isthmus. It is covered by water on 3 sides Isthmus - a narrow strip of land that connects two larger landmasses & separates two bodies of water. 3. Meander is when a river develops into a wavy or curvy flow. Much like a snake. 4. Sea Cliffs are high rocky coasts that plunge to the edge of the sea. They are the results of the erosional action of water and wind. 5. Plains are flat and broad land areas. Abyssal Plains are plains found in the deepest part of the ocean. 6. Plateaus are table lands or flat-topped mountains. - A portion of lands elevated thousands of feet above their surroundings as a result of geological uplift. 7. Mountain Ranges, a series of mountains closely related in position and direction. A well known mountain range is the Himalayas.  - GR8 AP Mandigma BWESIT