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Earth Science Essentials: Chapters 1-7 Overview

Understand Earth's composition, rocks, earthquakes, seismic data, layers, plate tectonics, weathering, and erosion. Includes key concepts and study guides.

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Earth Science Essentials: Chapters 1-7 Overview

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  1. Overview of chapters1-7

  2. Chapter 1: • The Earth is not a perfect sphere because it is wider around the Equator compared to the Poles. However it LOOKS perfect in our eyes! • The composition of the troposphere (lower layer of the atmosphere), hydrosphere and crust can be found on p. 10 in the ESRTs. • Latitude lines run across the globe (like from E to W) but are measured as North or South of the Equator. Longitudes run from Pole to Pole (like N to S) but are measured as East or West of the Prime Meridian.

  3. Ch. 1 continued… • You can find North by looking for Polaris (the North Star) – it can be found by lining up the “pointer stars” in the “cup” of the Big Dipper! (See p. 17 in your review book.) • Your latitude = the angle to Polaris if you are north of the Equator. • Every 15 degrees of Longitude change = 1 hour solar time difference. • Isolines connect points of equal value on a map. These can be measurements of many different things, including temperatures, elevations, air pressure, pollution levels, volcanic ash thickness…

  4. Ch. 1… • A profile can be drawn for a view across a map. You need a scrap of paper for this! (See p. 24 in the review book.) • Gradient – change in value/distance between 2 points. (See p. 1 in the ESRTs.) If isolines are close, the gradient is steep. • Contour lines make a “v” to the UPHILL direction when they cross a river!

  5. Ch. 2 • Minerals have well-defined physical and chemical characteristics (due to their internal arrangement of atoms) that help a person identify them. See p. 16 in the ESRTs. • Rocks are made up of 1 or more minerals. The 3 different rock categories are determined by the method by which they formed. • Igneous rocks formed from the cooling and solidification of molten magma or lava. The larger the crystal, the LONGER the cooling time. Small crystals = quick cooling. Glassy rocks = instant cooling – no crystals formed! Dark and dense = mafic. Light and less dense = felsic. (Except for black obsidian!) See p. 6 in the ESRTs!

  6. Ch. 2 continued… • Sedimentary rocks form from sediments piling up in water. Some sed. Rocks form from the chemicals that are left behind when water evaporates. Others form from organic remains. See p. 7 in the ESRTs! • Metamorphic rocks form when other types of rocks get changed from heat and pressure. Some of these rocks show “foliation” – banding or mineral alignment. This happens due to REGIONAL metamorphism. See p. 7 in ESRTs! • Only sedimentary rocks can have fossils.

  7. Ch. 3 • Earthquakes occur when there is movement along a “fault.” The first movement occurs at the “focus.” The point on the surface directly above the focus is called the “epicenter.” • P-waves travel faster than S- waves. P-waves can go through both solids AND liquids. S-waves only go through SOLIDS. Both waves travel faster through denser materials. • P. 11 in the ESRTs has a graph to find all sorts of earthquake info: • The distance to the epicenter can be found if you know the time difference between the P and S-waves. • Also, you can find the distance if you know the travel time for either the P or S-wave. • If you know the distance, you can figure out the time difference between the P and S-waves. • Etc.

  8. Ch 3….. • 3 circles must be drawn showing the epicenter distance for 3 places before you can locate the epicenter. (See p. 58 in your review book.) • Seismic data helps tell us about the layers of the Earth that we can’t see! There is a region of much higher density (the “Moho”) between the crust and the mantle. The outer core is a liquid. (See p. 10 in the ESRTs!) • We can infer the composition, density, pressures and temperatures of the layers of the Earth. (P. 10 in ESRTs)

  9. Ch 3…. • Meteorites tell us that the inner and outer core are mostly iron…and nickel! • The crust is moving in all sorts of directions due to the convection currents in the mantle. There are divergent, convergent and transform boundaries! (you can see examples on p. 5 AND 10 in the ESRTs) • Earthquakes, mountains and volcanoes all tend to appear near each other – near plate boundaries. • Hot spots are regions where heat flows upward from the mantle and causes volcanic activity on the surface. (P. 5 in the ESRTs!)

  10. Ch. 4 • Physical and chemical weathering break rock into smaller pieces. Know some examples of each type! (p. 81-82 in the review book) • Chemical weathering happens faster in WARM, MOIST climates – like Florida! • Soils form from the weathering of rock material PLUS the activity and decay of biological material – like worms, plants, fungi and insects…

  11. Ch 4….. • Weathered material may become small enough to be easily eroded. Erosion happens via 4 methods: gravity, water, wind and glaciers (GWWG.) • The erosional method that moved a rock will leave clues: • Gravity == jagged, angular, unsorted, bottom of cliff. • Water == rounded, smooth. Makes “V”shaped valleys. • Wind == only moves the smallest particles – sand, silt and clay. May be pitted or frosted…or have a strange triangular shape (a “ventifact”) • Glaciers == can move ANYTHING! Leaves striations – scratches –grooves. May put large boulders (“erratics”) in odd places. Makes “U”shaped valleys.

  12. Ch. 4…. • Depositional clues can let you know what did the moving. Examples: • Gravity = bottom of the cliff –mixed sizes (unsorted) • Water = separated by size –largest settle first, as soon as the water slows down. They may be “graded” – layered. • Wind = only small particles – may form sand dunes that are shaped by the wind. (gentle side = where the wind is hitting first, steep slope = the other side of the dune) • Glaciers = unsorted, unconsolidated sediments. May form low hills (Drumlins) that have a steep end and a pointy end. The steep end points “North” – which is the way the glaciers came from. The pointy end points “South” – showing the way the glacier at moved.

  13. Ch 4….. • The landscape of an area is shaped by the methods of erosion and deposition that are the most prevalent. Also, the bedrock type influences the shape of the landforms. See p. 2 and 3 in the ESRTs for examples! • Rivers will form special patterns depending on the landforms.

  14. Ch. 5: • Scientists use the following concepts to help determine the order of events that happened in the past: • Uniformitarianism (The events in the past happened at the same rate and in similar ways that they happen today.) • Superposition (The oldest rocks in the layers are at the bottom – as long as there has been no overturning,…etc.) • Original Horizontality (The rock layers were most likely laid down horizontally, so if they look different now, they were affected by something that came after them!) • Cross Cutting, Intrusions, Extrusions etc. (Rocks that are AFFECTED BY another process are older than that process. Look for signs of contact metamorphism (cm) to see which came first.)

  15. Ch. 5… • Pages 8 and 9 in the ESRTs are invaluable! • Pay attention to the index fossil names and letters across the top of pgs. 8 and 9. Find the exact times that these organisms lived. • Index fossils are: W i d e s p r e a d but lived only a short time.

  16. Ch. 5… • Absolute age can be determined by looking at the ratio of certain radioactive elements compared to their decay (daughter) product. If there’s a 50:50 split, then 1 “half-life” has passed. If there is a lot more decay product, then more that one “half-life” has passed. See p. 1 in the ESRTs for examples.

  17. Ch. 6 and 7 • The structure of our atmosphere can be found on p. 14 in the ESRTs. • Air pressure is affected by altitude, temperature and humidity. These 3 things all have an “inverse” affect on the air pressure. When either altitude, temperature or moisture levels go UP, the pressure goes DOWN. • The charts on p. 12 in the ESRTs are VERY IMPORTANT! Remember to subtract the wet-bulb temp from the dry-bulb temp before using the charts. • When there is more moisture in the air, both the dewpoint AND the relative humidity rise. When temp and dewpoint are getting closer, the chance of precipitation increases.

  18. Ch. 6 and 7…. • Wind is caused by differences in air pressure which can be caused by differences in air temperature. Facts about the wind: • Winds always blow from high pressure to low. • Winds are named for where they came (from). • When isobars are close, winds blow the most! • The Coriolis Effect makes winds in the Northern Hemisphere blow this way: Low = inward, counterclockwise High = out, clockwise

  19. Ch. 6 and 7….. • Know your weather instruments! • Clouds form when air RISES, EXPANDS and COOLS to DEWPOINT. Water vapor condenses. • You need condensation nuclei to make a cloud. • LOW pressure leads to cloud formation (because air is rising!) but HIGH pressure makes the skies clear! (because air is sinking!)

  20. Ch. 6 and 7… • Most weather systems move across the U.S. from southwest TO northeast. • Most of the sun’s energy goes into the evaporation of water. This energy is RELEASED when water condenses (like during cloud formation!) • Air Masses (different moisture and temperature characteristics) determine an area’s weather. cP = dry, cold mT = moist, warm… (see p. 13 in ESRTs)

  21. Ch 6 and 7… • Use p. 13 in the ESRTs to see the front symbols (they point in the direction that the front line is moving!) and the synoptic weather map station symbol. • DOUBLE CHECK the synoptic weather station symbol!! No units or labels are used. The temps are in Fahrenheit. The air pressure is in millibars, but is shortened to only the LAST 3 DIGITS. When you convert back, you either put a “9” or a “10” in front of these 3 numbers. Put a decimal between the last 2.

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