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Minerals
Mineral: A mineral is a naturally formed, inorganic solid that has a definite crystalline structure. A mineral can be either an element or a compound.
Element: An element is matter that only has one kind of atom. The Periodic Table lists all the known elements. Elements are pure substances that cannot be broken down into simpler substances.
Compound: A compound is a substance formed when atoms of two or more elements join together by chemical bonds.
Crystal: A crystal is a solid geometric form of mineral produced by a repeating pattern of atoms that is present throughout the mineral.
Silicate Mineral: Minerals that contain the two most common elements in the Earth’s crust, Oxygen and Silicon, and one or more metals.
Nonsilicate mineral: A mineral that does not contain compounds of silicon and oxygen.
Luster: The way in which a mineral reflects light
Streak: The color of the powder of a mineral
Fracture: The manner in which a mineral breaks along either curved or irregular surfaces
Hardness: A measure of the ability of a mineral to resist scratching
Density: The ratio of the mass of a substance to the volume of a substance
Rock Cycle
Rock: A rock is a naturally occurring solid mixture of one of more minerals and/or organic matter
Rock Cycle: The series of processes in which rock forms, changes from one type of rock to another, is destroyed, and forms again by geological processes.
Source: Prof. Steve Gao
Erosion: The process by which wind, water, ice or gravity transports soil and sediment from one location to another
Deposition: The process in which material is laid down. Low-lying areas collect sediment. As sediment builds up over time, its own weight presses the sediment together. Minerals dissolved in water precipitate and cement the grains of sediment together forming sedimentary rock.
Uplift: Uplift is movement within the earth that results in rocks being moved to the surface. Once rocks are exposed, weathering, erosion and deposition begin.
Weathering: The process in which water, wind, ice, and heat break down rock.
Composition: The chemical makeup of a rock. Composition describes either the minerals or other materials that make up the rock. In other words, the composition of a rock depends on the minerals the rock contains.
Texture: The quality of a rock that is based on the sizes, shapes, and positions of the rock’s grains - can be fine, medium, or coarse. Fine texture means the magma cooled rapidly; coarse texture means the rock cooled slowly.
Igenous & Sedimentary Rock
Igneous Rock: Igneous rock forms when hot liquid rock, or magma, cools and solidifies. Igneous rock also forms from Lava. Forms in 3 ways:When Rock is heated; When Pressure is released; When Rock changes composition.
Heating: A rise in temperature can cause the minerals in rock to melt. Different melting points cause some minerals to melt while other minerals remain solid. (Chocolate Chip Cookies).
Pressure: The high pressure deep within the Earth forces minerals to remain solid. When hot rock rises to shallow depths, the pressure in the rock is released (or reduced), and the minerals can melt.
Composition: When fluids such as water combine with rock, the composition of the rock changes, which can lower the melting point of the rock enough to melt it.
Extrusive: Extrusive Igneous rock is magma that was extruded on the surface of the earth (lava), and cooled rapidly.
Intrusive: Igneous rock is magma that cooled slowly inside the earth.
Sedimentary Rock: Sedimentary rock forms at or near the Earth’s surface. It forms without the heat and pressure that are involved in the formation of igneous and metamorphic rock.
Strata: Through the process of erosion, rock and mineral fragments (sediment) is deposited in layers (stratification). Many layers are strata., one layer is a stratum.
Composition: Clastic sedimentary rock is made up of rock and mineral fragments (clasts) that get cemented together. Chemical sedimentary rock forms when crystals precipitate out of solution (like halite). Organic sedimentary rock is made from the remains of living organisms - fossils (e.g., coal, limestone)
Structures: The most important feature of sedimentary rock is stratification, the process in which sedimentary rocks are arranged in layers. Sedimentary rock can also record natural processes, like wind (dunes), tides (ripple marks), tidal zones (mud cracks), even rain drops.
Geologic Dating
Principles of Superposition: Oldest rock at the bottom of a series of layers, new rock on top.
Original Horizontality: Sedimentary rock is deposited in flat, horizontal layers.
Lateral Continuity: Rock layers extend in all directions until they terminate (thin-out).
Principal of Cross-Cutting Relationships: A fault or igneous intrusion is younger than the rock it cuts across.
Principal of Fossil Succession: Fossils succeed one another through time, in a predictable sequence, and this can help date rock layers.
Principal of Inclusion: A rock containing a fragment from another rock must be younger than the fragment.
Relative Dating: Determining whether a rock is older or younger than its neighbor or some other geological feature - relative dating simply means figuring out what happened in what order. For example: You see a fallen branch in the snow. Beneath the fallen branch are footprints. The footprints took place before the branch fell, so they are older than the event of the branch falling (Superposition)!
Radiometric Dating: The process by which the absolute age of a rock or geologic event is determined. Radiometric Dating uses radioactive isotopes that decay by emitting nuclear particles.
Isotope: An alternate form of an element that has the usual number of protons but a nonstandard number of neutrons.
Parent Isotope: The original unstable isotope.
Daughter Isotope: What the parent isotope changes into.
Half-life: The time needed for ½ of a sample of a radioactive parent isotope to decay into a daughter isotope. By looking at how much of each type of isotope is present, we can calculate how old the rock is!!
Fossils & Geologic Time
Fossils: The remains or physical evidence of an organism preserved by geologic processes. Remains - Bones, Shells, other "Hard Parts" Physical Evidence - Trace Fossil, Mold, Cast
Trace Fossils: Fossils that are made by animals, but are not the animals themselves.
Mold: A cavity where a plant or animal was buried.
Cast: Created when the mold is filled with materials and becomes rock.
Index Fossil: A fossil that is wide spread (large geographical area) and short lived (only lived for a few million years). This kind of fossil is only found in thin rock layers of only one geologic age, or part of an age, and can help establish the age of the rock.
Geologic Time Scale
Source: EarthSci.org
Plate Tectonics
Earth’s Structure: The earth is layered as shown in the diagram below
Source: USGS
Lithosphere: The crust and the upper part of the mantle. This is what tectonic plates are made of.
Asthenosphere: A plastic layer (solid rock that moves very slowly) of the mantle on which the tectonic plates move.
Mesosphere: The strong lower part of the mantle.
Outer Core: A liquid layer that surrounds the solid inner core.
Tectonic Plates: Make up the lithosphere and fit together much like a giant jigsaw puzzle. Some plates don’t have continents on them, and others only have a part of a continent on them. (Diagram below)
Source: Prof. Steve Gao
Subduction: When plates collide, the denser plate (ocean crust above) is subducted beneath the less-dense continental crust. When this happens, we get earth quakes, volcanoes, deep sea trenches, and mountains. As these plates move around and bump into each other, many of the Earth’s features are created including mountains, deep ocean trenches, and island arcs. (Diagram Below)
Source: USGS
Plate Boundaries: Where plates meet, they can either move away from each other, move towards each other, or move past one another. (Diagram Below)
Source: Prof. Steve Gao
Astronomy - Big Bang
Cosmology: The study of the origin, structure, and future of the universe. Like other scientific theories, theories about the beginning and end of our universe are tested by observations and experiments. To understand how the universe formed, scientists study the movement of galaxies and make careful measurements. These measurements show that the galaxies are moving apart.
Expanding Universe: To get an understanding for how the galaxies are moving relative to each other, consider a loaf of raisin bread before it is baked, and then consider what happens to the raisins while the loaf bakes. They are carried with the dough, they do not travel through the loaf!
Galaxies as Raisins: As the universe expands (like the loaf of bread rising as it bakes), the galaxies move farther away from each other. There is no "center" to the expansion of the Universe!
Cosmic Background Radiation: The heat left over from the big bang was accidentally discovered in 1964.
To understand this radiation, think about what happens when you leave the oven door open after baking a loaf of bread. Eventually, the heat warms the room, and the oven and room reach the same temperature. The big bang theory says the energy from the initial "bang" was distributed in every direction.
Age of the Universe: About 13.7 Billion Years Old. Scientists calculate the age of the universe in 2 ways:
1. They measure the distance from Earth to other galaxies, figure out how fast we are moving, and estimate the age of the universe from that data. (The same as: if we are 50 miles from Boston and will drive to Boston at 50 mph, how long will it take to get to Boston?)
2. Another way is to calculate the age of old stars. The universe has to be at least as old as the oldest star/object it contains, so finding the oldest object gives us an idea of how old the universe is.
Astronomy - Solar System
The 9 Planets: My Very Excellent Mother Just Served Us Nine Pizzas. 1st 4: Terrestrial (inner, rocky); next 4: Jovian (outer, gas giants). Pluto doesn’t fit the model, and the Asteroid Belt is a "missing Planet".
Meteor: Flash in the sky (so-called shooting star) - does NOT hit the Earth’s surface
Meteorite: Hits the surface of the Earth (small strikes happens every day)
Asteroid: Really big chunk of rock and/or Iron; technically still called a meteorite if it makes it to the Earth’s surface (killed Dinos 65 million years ago)
Comet: "Dirty Snowball" made of dust and frozen ice.
Nebula: All of the ingredients for building the sun and planets are found in the seemingly empty space between the starts in clouds called nebulas - mixtures of gases and dust.
Nebular Theory: Gravity pulls matter together, but pressure pushes matter apart. Gas in a nebula is very thin, and not especially hot. Temperature is the measure of how fast the particles in an object are moving. Low temp = slow movement; high temp = fast movement. As particles bump into each other, the collisions cause the particles to move away from each other, which results in pressure (expansion). The balance between pressure and gravity in a nebula can be upset by another nebula colliding with the first, or from a compression wave from a nearby Nova (exploding star) or Super Nova (big exploding star).
Globules: Small regions of the nebula are compressed, or pushed, together forming globules - areas of gas and dust that contract under their own gravity. As the matter in a globule collapses inward, the temp increases and the stage is set for stars to form.
Solar Nebula: The cloud of gas and dust that formed our solar system. It is thought to have formed as described above. It took the solar nebula about 10 million years to collapse and form our solar system. As the nebula collapsed, it became denser and the gravitational attraction increased. The center of the solar nebula became very hot and dense, and the gas and dust began to slowly rotate around the center of the cloud as it got pulled into the dense center (conservation of angular momentum). While the pressure at the center was not enough to balance the pull of gravity, the rotation began to flatten the nebula into a disk (like "throwing a pizza"). All of the planets still follow this rotation today!
Planetesimals: As bits of dust collided, some stuck together to form golf ball-sized bodies, that began to stick to each other, and eventually formed planetesimals - bodies hundreds of kilometers in diameter. Some of these planetesimals formed the core of the current planets, while others collided with the forming planets creating larger planets, enormous craters, and also the Earth’s moon (from debris left over from an impact with a mars-sized body). Some planetesimals were far enough from the sun that their gravity could only attract nebular gasses (the Sun was collecting most of the heaver bodies). These outer planets grew to huge sizes and became the gas giants - Jupiter, Saturn, Uranus, and Neptune. Closer to the center of the nebula, temp was too high for nebula gases to hang around - the pressure blew them to the outer part of the flattening nebular disk.
Solar Ignition: As the planets were forming, the center of the disk became so hot and dense that hydrogen isotopes began to fuse (join) to form Helium. Fusion releases huge amounts of energy and created enough pressure to balance the gravity pulling everything together (combined with rotation). When the gases stopped collapsing, our sun was born and a new solar system was complete. The outward pressure from "ignition" blew Earth’s first atmosphere away (it was mostly hydrogen) towards the out planets.
Astronomy - The Oldest Science
Ptolemaic Theory: Ptolemy wrote a book (140 CE) containing all of the ancient knowledge of astronomy he could find and created what has become known as the Ptolemaic Theory. In his theory, Earth was at the center of the universe and everything else revolved around it! Although the theory was incorrect, it correctly predicted the motions of the planets. This was the prevailing view of the universe for over 1500 years!!
Copernican Theory: Copernicus, a Polish Astronomer, wrote a book in 1543 that revolutionized Astronomy. According to his theory, the sun is at the center of the universe and everything else, including the Earth, orbits the sun!! The Copernican Revolution took place, and all of science and society changed!
Galileo: Used his telescope to observe the planets in 1609 and discovered craters on the moon, discovered four of Jupiter’s moons, sunspots on the sun, and more.
Isaac Newton: Discovered gravity in 1687 by demonstrating that every object in the universe attracts each other. The force of gravity depends on the mass of the objects and the distance between them. Newton’s law of gravity explains why all of the planets orbit the massive sun at the center of our solar system.
Modern Astronomy: Modern tools have allowed us to discover so much about the universe, but most of what we call "modern astronomy" didn’t happen until the 1920s!
Edwin Hubble: Proved in 1924 that other galaxies existed beyond our Milky Way. Until that time, Astronomers thought that the Milky Way was all that existed!
Today: Larger and better telescopes on Earth and in space, computer models, spacecraft, and the study of meteorites, allow scientists to better understand the true nature of our planet, our solar system, our galaxy, and the universe! Not until the late 1960s (1st Satellites) and early 1970s have we begun to really understand our place in the universe!
Astronomy / Climate / Weather
Year: The time is takes Earth to orbit once around the sun (currently 365.24 days)
Month: The time it takes for the moon to orbit once around the Earth (29.53 days)
Day: The time it takes the Earth to rotate once on its axis (23 hours, 56 minutes)
Rotation: The spinning of the Earth on its axis. This gives us "day" and "night".
Revolution: The Earth’s movement in orbit around the Sun. This gives us the "seasons".
Seasons If the Earth rotated on an axis that was perpendicular (straight up-and-down), the length of day and the length of night would be the same (12 hours) everywhere on Earth. If the light from the Sun strikes the Earth from the right, then the left half of the planet would be dark. As the Earth rotates through the light from the Sun, an equal amount of the planet would remain "day" and "night". If you measured the distance along lines of latitude on either side of the "day-night" line (the Circle of Illumination), you would get the same distance. That is another way of saying, you have the same number of hours of day and night. Because the Earth’s axis is tilted 23.5°, more of the "top" of the Earth receives sunlight in "summer" than in "winter"! When the North Pole is tilted towards the Sun, those of us who live in the Northern Hemisphere call this "summer", but if you happen to live in Australia, you would call this "winter". As the Earth revolves around the Sun, the Northern Hemisphere will "lean" towards the Sun and away from the Sun as we move from one season to tne next.
Equinox: "Equal Night". When the length of day and night are equal. Problem is, the Earth doesn’t rotate on an axis that is perpendicular. Earth’s axis is tilted 23.5°. This means "day" and "night" are not always the same everywhere. The tilt results in longer and shorter day length.
Insolation: The amount of solar energy received by the Earth.
Solstice: "To Stand Before The Sun" A solstice is when the Sun travels to its highest point in the sky.
Astronomical vs. Climatological Seasons: Astronomical seasons lead climatological seasons. The first day of Winter is ~December 21st are marks the date when the days start getting longer. However, "warm" weather does not arrive for some time. Why does it take from December 21st or 22nd (Winter Solstice) to March 21st or 22nd (Vernal Equinox) for things to start warming up?
Hysteresis: Think back to the days of Chemistry when conduction, convection, and radiation were discussed
Conduction: The Sun’s energy is in the form of radiation. This radiation heats the land and water. How does the heat travel through the land and water? This takes about 3 months.
Weather Basics
Polar Front: Where cold polar air meets warmer air. These are meanders known as Rossby Waves, but are also commonly referred to as the "Jet Stream."
Source: City University of New York
Jet Stream: Fast moving "jets" of air in the upper troposphere located where cold and warmer air masses meet.
Source: City University of New York Geography Dept.
Mid-latitude Cyclone: What we call "storms" that form out of meanders in the Polar Front:
Source: Prof. Steve Gao
This is how we see Mid-latitude Cyclones (Storms) during a weather forecast:
Source: Oaklahoma Climatological Survey
With these symbols used to show us where the "fronts" are located:
1 - Early stage; 2 - Open stage; 3 - Occluded stage.
Red semi-circles indicate warm air, Blue triangles indicate cold air
Clouds: Clouds are classified based on height and form as shown below: (e.g., nimbus means "rain")
Source: Staffordshire University Web Site
A warm front creates a progression of cloud types beginning with cirrus (can be as many as 600 miles ahead of the front) and ending with nimbostratus (dark low cloud deck covering the entire sky with light to moderate rain of long duration). This progression usually takes from 12 to 24 hours. Warm air rises over cool air because it is less dense. Warm air holds moisture and that moisture will condense at high (cooler) altitudes. A cold front is fast moving and responsible for the vast majority of damaging weather. Cold (dense) air will push the warm air up and out of its way cause rapid could and storm formation resulting in thunderstorms, severe thunderstorms, and tornadoes.
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