Introduction to Earth Science

1. Introduction to Earth Science Chapter 1

2. Essential Questions • What does an Earth Scientist study? • What information do various maps give to an Earth Scientist? • How do Earth Scientists (and all scientists) seek knowledge?

3. Overview of Earth Science • Earth science is the name of the group of sciences that deals with Earth and its neighbors in space. • Earth science is divided into four broad categories:

4. The Earth Sciences • Geology—the study of the solid Earth • Oceanography—the study of the Earth’s oceans • Meteorology—the study of the Earth’s atmosphere • Astronomy—the study of the Earth’s place in the universe

5. Formation of Earth • TheNebular Hypothesis suggests that bodies in our solar system evolved from an enormous rotating cloud called the solar nebula. • Mostly hydrogen and helium, with some heavier elements.

6. Differentiation • As the newly formed Earth cooled layers formed through a process called differentiation. • Denser elements (iron and nickel) sink to the Earth’s core. • Lighter rocks and materials migrate outward forming the mantle and crust.

7. A View of the Earth • Earth can be thought of as consisting of four major spheres: • Hydrosphere • Atmosphere • Geosphere • Biosphere

8. Earth’s Major Spheres • The hydrosphere includes all liquid water on Earth—both saltwater and fresh water. • The atmosphere consists of the gaseous envelope surrounding the Earth. • Although the atmosphere extends more than 100km up, 90% is within 16km of the surface.

9. Earth’s Major Spheres • The biosphere includes all life on Earth. • The biosphere is concentrated in a zone that extends from the ocean floor upward several kilometers in the atmosphere. • The geosphere consists of the solid parts of the planet and is not uniform. • Based on differences in composition it is divided into three main regions, the core, the mantle, and the crust.

11. Geosphere Divisions • The dense core has two parts; a solid inner core and a liquid outer core. • The rocky mantle is divided into an lower mantle and upper mantle. • The rock in the upper part of the upper mantle is somewhat flexible and pliable—it’s called the asthenosphere (weak sphere).

12. Geosphere Divisions • The outer crust is divided into continental crust and oceanic crust. • This rigid outermost layer is called the lithosphere (rock sphere).

14. Plate Tectonics • The lithoshpere is broken into several sections called plates. • The Theory of Plate Tectonics states that earthquakes, volcanoes, mountain building, and the movement of continents are the result of the movement of lithospheric plates.

15. Representing Earth’s Surface • Specifying a location on Earth’s surface is done using a grid system of latitude and longitude. • Latitude is the distance north or south of the equator (measured in degrees). • Longitude is the distance east or west of the prime meridian (also in degrees).

16. The Global Grid

19. Maps and Mapping • No matter what type of map is made, some portion of the surface will always appear too small, big, or out of place. • Cartographers (mapmakers) have found ways to limit the distortion of shape, size, distance, and direction.

20. The Mercator Projection • Made by taking slices of a globe’s surface and stretching the ends to meet. • Directions accurate • Size and distance distorted.

21. Robinson Projection • Shows most distances, sizes, and shapes accurately. • Distortions present along edges.

22. Other map projections: • A conic projection is made by wrapping a cone around the Earth at a particular line of latitude. (almost no distortion at that line) • A gnomonic projection is made by placing a sheet of paper on a globe so that it is touching only one spot. • See page 13 in text.

23. Topographic Maps • Topographic maps show Earth’s elevation using contour lines. • All spots along a particular contour line have the same elevation.

24. Topographic Maps • The contour interval on a topo map gives the user the difference in elevation between each contour line. • Geologic Maps are those that also contain information about the type and age of rock formations in the area.

25. More on maps • All maps represent a certain area so a scale is included to compare actual distances. • Satellites have made accurate cartography much simpler than in the past.

26. Earth System Science • Earth system science aims to study the Earth as a system made up of numerous interacting parts, or subsystems. • A system can be any size group of interacting parts that form a complex whole.

27. Earth as a System • The Earth system is powered by two sources of energy: • The Sun– which drives external processes in the atmosphere, hydrosphere, and at the surface. • The Earth’s interior heat—which drives plate tectonics.

28. Each system affects the other. • The actions of nature and people produce changes in all of the other parts of the Earth system. • Resources (some renewable, some not), population, pollution, global warming, species extinction, etc. are some examples.

29. Scientific Inquiry • All science is based on two big assumptions: • The universe behaves in a consistent and predictable manner. • Through study, we can understand this behavior.

30. Hypothesis • Once observations have been made and data gathered, scientists try to explain how or why things happen in the manner observed. • They state a possible explanation called a scientific hypothesis.

31. Theory • Once further observations have been made and/or tests performed, scientists either accept, modify, or reject their hypothesis. • The hypothesis is elevated to a Scientific Theory once it has been well tested and accepted by the scientific community as the best explanation of observable facts.