Chapter 1 : Introduction to Earth Science

1. Chapter 1: Introduction to Earth Science Section 2: A View of Earth Section 3: Representing Earth’s Surface

2. Section 2: A View of Earth • Key Concepts • 4 major spheres into which Earth is divided • 3 main parts of the solid Earth • Theory of plate tectonics

3. Earth’s Major Spheres • 4 major spheres: • Hydrosphere • Atmosphere • Geosphere • Biosphere

4. Hydrosphere • All water on Earth • Oceans: ~97% • Fresh water (lakes, streams, groundwater, glaciers): ~3%

5. Atmosphere • Reaches beyond 100 km above Earth • 90% occurs within 16 km of Earth’s surface • Provides protection from Sun’s heat & radiation • No atmosphere life would not exist • No erosion/weathering surface resemble moon

6. Geosphere • Beneath atmosphere & ocean • Not uniform • 3 main parts (composition): • Core: dense • Mantle: less dense than core • Crust: lightest & thin; oceanic/thinner, continental/thicker

7. Biosphere • Includes all life on Earth • Ocean floor up into atmosphere • Without life, the makeup & nature of the other spheres of Earth would be very different. Biosphere building at U of Arizona

8. Plate Tectonics • 2 types of forces affecting Earth’s surface: • Destructive forces: weathering, erosion • Constructive forces: mountain building, volcanism • Theory of plate tectonics emerged early 20th century • More than 50 years later hypothesis theory • Explained how EQ and volcanic eruptions occur and how continents move. • Plates motion driven by unequal distribution of heat

9. Section 3: Representing Earth’s Surface • Key Concepts • Lines on the globe & location • Mapmaker challenges • Topographic maps vs. other maps

10. To locate places N or S on Earth, cartographers use… • Latitude: distance in degrees North/South of Equator; lines that run parallel to Equator • Equator: 0°runs horizontally equidistance from the poles • points North of equator= degrees N • points South =degrees S

11. To locate places E or W on Earth, cartographers use… • Longitude: distance in degrees E or W of the prime meridian • halves of giant circles running thru Earth • Long. lines aka meridians • Prime meridian: 0° long. • runs through Greenwich, England-- Royal Naval Observatory • Points west of PM designated W • Points east of PM designated E • International Date Line: 180°long • Note convergence of longitude lines as you approach the Poles…1° long=111km at the equator and 0 km at the poles

12. Degrees, minutes, seconds • To precisely describe the latitude of a place degrees, minutes and seconds are used. It looks like: ##°##’##” • Why it matters? See below! • 1º lat=111 km on Earth’s surface =(40,000 km circumf./360°) • 1’ lat=1.85 km on Earth’s surface =(111 km/60’) • 1” lat=.03 km on Earth’s surface =(1.85 km/60”) Minutes and Seconds For precision purposes, degrees of longitude and latitude have been divided into minutes (') and seconds ("). There are 60 minutes in each degree. Each minute is divided into 60 seconds. Seconds can be further divided into tenths, hundredths, or even thousandths. 

13. Types of Maps • Globes (not a map) • Projection Maps • Mercator projection • Robinson projection • Conic Projection • Gnomonic Projection • Topographic Maps • Geologic Maps • Legends & Scales

14. Globes • Mapmakers wanted to present information accurately • Mimics shape of Earth • Can’t be complete enough to be useful for finding directions and can’t be small enough to be convenient for everyday use.

15. Projection Maps • Imagine a light inside a globe shining out. Wrap a clear transparency around the globe. Trace the outline of the shadow of the land on the transparency. • Takes the round globe & flatten it out Pro: Easy to travel with Con: Creates a lot of distortion at poles • Types: Types Visually • Mercator • Conic • Robinson • Gnomonic Proportional? flattening the earth animation flattened globe to map

16. Robinson • Most widely used • Pro: Show most distances, sizes, and shapes accurately • Con: distortion around edges of map

17. Mercator Projection • Sheet wrapped around the globe • Creates parallel lines of lat & long Pro: straight lines allow easier navigation (planes/ships) Con: lots of distortion of land shapes as you reach higher latitudes • Greenland appears as big as S. America but it’s really 1/8th the size of S. America!!

18. Conic Projection • Areas below red line would appear HUGE as areas near poles look smaller. • Projecting points/lines from globe onto cone @ lines of latitude • Pro: Little distortion of spots touching cone/ line of lat., used to map small areas (road/weather maps) • Con: Lots of distortion near top and bottom of map

19. Gnomonic Projection • Points/lines from globe projected on paper that touches globe at 1 point • Pro: No distortion at contact point • Con: Lots of distortion in direction & distance between landmasses • Note little distortion near Greenland & much in the S. US • Great accuracy the shortest distance between two points—straight line great for navigation!

20. Topographic Maps • Bird’s eye view of an area • Show Earth’s 3-D in 2-D • Shows how steep/gentle a slope is • Shows the elevation & shape of the land and other geographic or cultural (bridges, schools, churches, cemeteries, etc) features

21. Vocab: Topographic Maps • Contour lines: connect points of equal elevation • Contour interval: difference in elevation between adjacent contour lines • Relief: difference in elevation between highest & lowest points on map • Index contour: every 5th line on the map is bold and elevation is marked for reference

22. Contour line rules… • Contour lines are continuous closed loops; they never just appear or end on a map except at the edges • Separate higher elevations from lower elevations • Never cross (run together=cliff) • Closer lines=steeper slope • Closed depressions are marked with hachures (point in direction of drop) • Water flows perpendicular to contour lines

23. Geologic map • Color coded to show rocks below the soil • Distribution • Arrangement • Type of rock/minerals • Age of rock • Often superimposed over topographic maps

24. All maps have… Map Legends Map Scales Shows distances on a map Ratio between distances on map and actual distances on Earth’s surface • Shows symbol images • Decodes their meanings

25. Remote Sensing: gather data about Earth using instruments on satellites, planes or ships; more accurate • Landsat satellites • Weather satellites • Navigation satellites • Very Long Baseline Interferometry (VLBI) • Global Positioning System (GPS) • Geographic Information System (GIS)

26. Landsat • Satellites detect features based on the warmth (diff frequencies) they radiate • Detectors on mirrors measure the intensity of energy received digital images

27. Weather Satellites • Monitor atmospheric temperature, humidity, cloud cover, etc. • Help locate sources of distress signals • Able to scan surface in one 24-hour period The first picture of Earth from a weather satellite, taken by the TIROS-1 satellite on April 1, 1960. Although primitive in comparison with the images we now receive from satellites, this first picture was a major advance.

28. Navigation Satellites • Assist ships and submarines to determine location

29. Very Long Baseline Interferometry (VLBI) • Utilizes large network of antennas globally to receive radio waves from space objects (quasars) • Using the arrival times of radio waves from quasars, the position of radio telescopes on Earth are determined to within millimeters of their position. • Able to study tectonic plate movement  due to changes in telescope position

30. GPS[Global Positioning System] • Satellite navigation system using microwaves • 27 satellites 12,000 miles from Earth • Constantly orbit • Orbit Earth twice/day • Accuracy 10 m • Triangulate location based on signals received from 3 sats. • Signal from 4 sats. would allow for elevation calculations • GPS tutorial

31. Importance of Triangulation • Able to pinpoint given location • Minimum of 3 satellites needed to triangulatewhere all 3 circles intersect is where your given location is!

32. GISGeographic Information System[computer based program] • Combines map types we’ve discussed • Layers info one on top of another • Topography of land • Elevation • Roads, buildings, etc • Monitor changes to a specific area over time • Volcanic eruptions • Flooding of an area • Animal population trends • Define vector/raster!