Science OGT Study Guide

Pregunta	Respuesta
Image: convection_currents.PNG (image/PNG)	a= Mantle, b= Crust, c= Convection Currents, d= Core
Plate Tectonics	The theory that the Earth's crust is broken up into a number of large plates that move and interact.
Convection Current	The transfer of heat by flowing action within a liquid or a gas; the heat rises, cools, and sinks over and over again i.e. convection currents in the mantle that move the tectonic plates
Core	The Earth's center, made of most nickel and iron.
Mantle	A thick layer of rock below Earth's crust; it's solid, but flows very slowly.
Crust	The outermost solid rock layer of Earth.
Continental Drift	The theory proposed by Alfred Wegener which stated that the continents are drifting across Earth's surface.
What is some evidence for the Continental Drift Theory?	1. The continents fit together like puzzle pieces....2. Matching fossils were found on different continents.
Mid-ocean ridge	Underwater mountains that extend into all oceans. This ridge is created by divergent plate boundaries.
Sea-floor spreading	New ocean crust created at mid-ocean ridges as older crust moves away.
Subduction Zone	When an ocean plate collides with a continental plate, the ocean plate tends to slide under the continental plate.
How are mountain ranges created?	Convergent plates collide and push up.
Earthquakes	A natural disaster happening when transform plates slide past one another.
How are islands formed?	When volcanoes erupt (magma rises from within the Earth) and the magma cools i.e. Hawaiian Islands
Folding & Faulting	The movements of plates that can cause rocks to bend, fracture, and slide.
Relative Time Scales	They determine age by the sequences of rocks.
Absolute Dating	Finding the actual date and age.
Some rocks contain elements with unstable isotopes that decay slowly over time. They will decay into a different element that is stable. This change occurs at a rate called a ____ ____- amount of time required for half a sample of the radio active isotope to decay	half life
Big Bang Theory	The theory that the Earth was created in one giant explosion billions of years ago, and is constantly expanding today from this location.
Red Shift	Displacement of a star's light toward the red end of the spectrum, caused by an increase in distance from the star and the observer. Red shift is evidence for the big bang theory.
How does a star form?	The gravity produces great heat, when hot enough, nuclear fusion occurs which causes hydrogen protons to join together producing the massive energy just as our sun does.
Nebula	A cloud of dust and gas that are pulled together by gravity
Geocentric Theory	The theory that the earth is the center of the solar system. This theory is INCORRECT.
Heliocentric Theory	Copernicus proposed the theory that the sun is at the center of the solar system. This theory is CORRECT; Earth and other planets orbit the sun.
Cyanobacteria	The first life on Earth. The cyanobacteria lived in oceans, performed photosynthesis and released oxygen which helped put oxygen into the atmosphere.
How can you learn about the history of the Earth?	You can look fossils and rocks: Fossils can be used to match up rock layers that are far apart.

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	Creado por Niat Habtemariam hace casi 11 años