Mid- term Study Guide 2012-2013
Astronomy
*The tilt of the Earth causes the seasons. The Hemisphere (Northern or Southern) that is pointing toward the sun will always
be warmer due to more direct rays from the sun. When it is Winter in the northern hemisphere it is summer in the southern
hemisphere
*The solstices (winter and summer) occur during the times when the hemisphere is the closest or the farthest points away
from the Sun during the Earth’s yearly elliptical rotation. The point when the Northern part of the Earth is the farthest away
from the direct rays of the sun is the winter solstice. When the Northern part of the Earth is closest to the direct rays of the
sun we experience the summer solstice.
*All stars are powered by Nuclear Fusion *(Fusion ,NOT Fission. It has a “u” like the Sun!)
*Mars is windy and sandy. It is called “The Red Planet”. The high winds are responsible for creating huge Sand dunes on
Mars.
*Density =the Mass & Volume of an object (D=M/V Remember the song…”DMV, DMV..density ,density…..(haha!, It’s in
your head now isn’t it?!)
*Earth rotates once on its axis in 24 hours or 1 day causing day and night on the planet.
*Parallax is used to measure a stars distance away from Earth.(remember…hold out your thumb,close one eye….)
*When we view an object in space we can tell the difference between a planet and stars by observing the position change
over weeks or months. Planets move slowly so are not goingto see real change in an hour or so. It takes time to see a change
in positions!
*Absolute magnitude is the amount light a star actually gives off. Apparent magnitude is the amount light we see on
Earth(Could be different than the actual amount ,no?). A small star can appear bright if it is close to Earth. Brighter stars that
are far away may appear dim because of the distance away from the Earth.
*The order of the planets are Mercury, Venus, Earth, Mars, [ Asteroid Belt(Wait, OK, not a planet, but lies between Mars
and Jupter !) ], Jupiter, Saturn, Uranus, Neptune(My Very Excited Mother Just Served Us Nine Pizzas!)(And yes, I still
included Pluto,even though we all know it is now classified as a Dwarf Planet)
*Pluto a dwarf, planet has a highly unusual orbit that crosses Neptune's orbit and is actually closer to the Sun for a short
period of time. (Think Mickey’s dog, Pluto off his leash ! he’s crazy I tell you,so eccentric, crossing the path of others!)
*A light year measures DISTANCE! It is the distance that light travels in one year.
* Stars are distributed as clumps in the universe and these clumps are unevenly distributed throughout the universe.
*Earth is the only planet in the Solar system that contains liquid water. Why is this important you ask? Because it allows the
support of life!
*Most stars are made primarily of (mostly of) Hydrogen with some helium in the mix too..
MAPS
*Contour lines connect points of equal elevation. No matter where you are on that particular contour line, it will measure
the same elevation.
* Remember the closer the contour lines are together the steeper the location!!!
* Contour lines “V” in the upstream direction.(The pointy end of the “V” will point upstream)
*On a contour map, hachure lines show depressions on a mountain like a volcanic crater or a sink hole. They appear as an
oval with short lines inside of them (REMEMBER: A chicken egg shape with cracks. The chick “hatches” out of it!)
* The scale of a map is simply a ratio. It has no unit. Whatever unit you use on the map is worth the indicated ratio of that
unit on the ground in real life. ie.. 1:500 means 1 ft on the map would equal to 500 ft on the ground or 1 mile on the map
would equal to 500 miles on the ground, etc.
Minerals
 Virginia’s top mineral resources are Coal, Titanium, Limestone, and Granite. All resources can be conserved by Reducing,
reusing and recycling.
* Know the Mohs Scale of Hardness page 69 in textbook!* When using a scratch test to determine minerals hardness
lower numbers cannot scratch higher numbers. Higher numbers can scratch lower numbers.
* Minerals are comprised of one or more elements. It is the unique combination of these elements that account for the
variety of minerals(remember our element Gummy Bear lab!)
*We identify minerals due to a variety of different characteristics such as hardness, luster, streak, crystal shape, acid
reactivity, and magnetism
* Talc is the softest mineral and has a hardness of 1
* Quartz is found in sand and is used to make glass. It has a hardness of 7 on the Mohs Scale of Hardness
* Streak is a powder that gives us a minerals color we test for streak by rubbing against a harder material like a tile.
 All minerals share 5 basic characteristics they are solid, have repeating patterns of atoms called crystals, are formed from
natural processes(not manmade), inorganic(not living or from a living source), with a definite chemical compostition.
* Crystals are atoms that are made up of repeating patterns of atoms. Each mineral has it’s own unique crystal pattern
 A mineral that does not split apart evenly is known as fracture(looks like a big clump,no flat sides)(ex.Quartz )
*A mineral that breaks along flat, smooth surfaces has cleavage (looks flat)(ex. halite, mica)
 The silicates: Oxygen(O) and Silicon(Si) make up most of the rock forming minerals
 (Iron)Pyrite is another name for Fool’s Gold.(Why?)
* Gemstones are mineral crystals that are valued for their hardness, luster and color(ie.diamond(hardness-10)
topaz(hardness-8)
* Ore minerals are mined and smelted and the valuable/useful elements are extracted from the rock for profit(ex.hematite,
galena, graphite,and sulfur(which is bright yellow )
Rocks
*The most important characteristics of identifying how rocks were formed(way to identify them) are their texture and
composition

Sedimentary rocks have the most fossils found in them. Moreso than the other two types of rock.(Why?)
*Detrital Sedimentary rocks
are formed from weathering ,erosion, deposition(sedimentation),compaction and
cementaion(Remember the RICE CRISPY TREATS!)
*There are 3 types of sedimentary rocks: detrital(or clastic)(ex. sandstone), organic(ex. coal), and chemical(ex. rock salt)
 Metamorphic rocks will usually be found in areas where there is great pressure and heat like subduction zones.
The process that changes rock from 1 type to another over a long period of time is known as the rock cycle
The best way to identify any Igneous, metamorphic or sedimentary rock is through its composition and texture. (look at
grain/crystal shapes and sizes)
 Igneous rocks form from magma or lava. There are 2 types

Igneous intrusive(INSIDE) rocks which form underground, cool slowly and have large mineral crystals and
grains. Example: Granite

Igneous extrusive(EXITS) rocks form from lava on the surface that cool quickly outside and have small
crystals and grains or are glass like. Example: Obsidian (VOLCANIC GLASS)
* Metamorphic rocks have the following characteristics: Flattened crystals, colored parallel sections and can appear with
bent or curved lines. (The crystals/grains look bent or stretched in many cases) There are two types: foliated and nonfoliated.

Metamorphic rocks that have alternate colored bands are called foliated(banded). Ex: Slate, Schist,Gneiss
Non-foliated have no bands, maybe just some squiggly bands ie. Quartzite, and Marble


Minerals are composed of elements and Rocks are composed of minerals.
Limestone and granite are used to create crushed rock for the construction industry. Limestone is also used
to create concrete
Renewable and non-renewable resources
 The 3 R’s are Reduce, Reuse and Recycle * Aluminum has been the metal that we recycle the most
 Fossil fuels are non-renewable resources. They cannot be replaced easily so they will eventually run out.
 The fossil fuels are Coal, Natural gas, and Oil (petroleum)
 Wood is a renewable energy source however it does contribute to air pollution because of the smoke it gives off when it
burns.
* Hydroelectric energy is a renewable, low pollution energy resource however it can cause ecosystem destruction due to the
damming of free flowing rivers. *** Solar energy is the least polluting of all the renewable energy resources***
Plate Tectonics & Earthquakes
REFER TO ALL PLATE TECTONIC(CH10 begins page 272in text))AND EARTHQUAKE NOTES(CH11 begins page 304 in text)
*The theory of continental drift is supported by same fossils along continental edges, continents that fit together like a big
puzzle, similar rock structures.
*Earthquakes usually appear where tectonic plate boundaries are rifting, mid ocean ridges, transform boundaries,
and subduction zones
*Earthquakes are usually caused by a buildup of pressure between plates that causes on plate to slip or snap past another
plate
*Earthquakes originate at the focus which is usually underground. The epicenter is the point above the focus that is on the
surface.
3 Seismographs are used to determine the epicenter of an earthquake
Pangaea is a ancient supercontinent that helps prove the theory of continental drift.
Primary and secondary waves are created by Earthquakes. Primary waves travel faster and are always measured first.
*When two continental plates collide large mountains are formed.(convergence)
*A strike slip fault is when 2 pieces of crust slide horizontally past each other. Ex: San Andreas Fault
*All plate boundaries on the planet create earthquakes and usually volcanoes(if subduction is present) scientist use this data
to map the plate boundaries of Earth.