I. Introduction - the Importance of Earth Science

II. The Four Spheres or Reservoirs:

A. The Solid Earth: the Earth itself, esp. the lithosphere (rocky outer shell of Earth)

B. The Hydrosphere: Earth's water

C. The Atmosphere: Earth's gaseous envelope

D. The Biosphere: life

E. The interaction between the different spheres

III. Geology and the Methods of Science

A. All science is based on the assumption that the natural world behaves in a consistent and predictable manner.

B. How does it work? observation of natural processes, collection of facts

1. Formulation of hypotheses, usually multiple hypotheses. Need to test them!

2. Theories--widely accepted, well-tested

3. Scientific laws--an explanation that always works: no known exceptions! E.g. the Law of Gravity.

C. Scientists must be open to whatever they find, regardless of their hypotheses!

D. Peer review: other scientists evaluate (and retest, in some cases) work before publication

IV. Unifying Themes of the Dynamic Earth

A. Time and rate

B. Cycles and interconnections

C. Dynamic equilibrium

D. Energy exchanges (esp. convection)

A. Energy

B. Evolution (change over time)

C. The Environment

D. The Nature of Science

VI. The Energy Budget for our Dynamic Earth

A. Introduction

1. How and where does the Earth's energy originate? (internal/external)

2. How does it move?

3. What does it do?

B. The Sun (Solar Energy): the largest source External

1. Transport mechanism: radiation

2. Most converted to heat: evaporates water or moves air or ocean water

3. Lots reflected back to space (almost 1/3!)

4. Only 1/4300 caught by plants through photosynthesis and only a tiny fraction of that is stored in the Earth as fossil fuels

C. Tidal energy: the gravitational pull of our neighbors, esp. the Sun and moon, External

1. Tiny compared to the sun's energy

2. Powers the ocean tides, slows the Earth's rotation by ~2 sec per 100,000 yr

D. Kinetic energy from impacts: Internal

1. Trivial today but important during Earth's early history

2. Provided much of the heat for the "Iron Catastrophe" or "Iron Crisis" and origin of the Earth into layers based on physical differences:

a. Crust - low density, thin, outermost layer

b. Mantle - higher density, thick layer

c. Core - densest layer, thick, in the center of the Earth. Mostly metal: iron and nickel.

1. Inner core is solid

2. Outer core is liquid

3. Primordial heat from the early Earth history still being released today

E. Decay of radioactive isotopes: heat released by the steady decay of certain elements by nuclear fission, Internal

F. Contrast between internal and external energy

1. Internal heat (primordial and radioactive heat) minuscule compared to heat from external sources. However the effects of this heat can be mighty and catastrophic (volcanic eruptions, earthquakes, mountain building, etc.)

2. External heat (solar and tidal)