CHAPTER 1:An

Introduction to Geology

Geology is the Scientific Study of Earth and the Other Planets

• Physical Geology– Materials composing

planets– Processes acting on

those materials– Products formed as a

result• Historical Geology – Earth’s history– History of life on Earth Excavating

Fossils

Geology is Important in Everyone's Life!

• How are geologists involved in some of the examples shown here?

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Interaction between• Rocks, water, gases, • sediments and• living plants & animalsPowered by• Solar energy, gravity, • heat from Earth’s interior• These interactions are

known as Biogeochemical processes

• The Earth is continually changing!

Earth’s Surface is Actively Evolving!

Geologists recognize the importance of:• Human desire to use

resources• The critical need to

conserve natural resourcesTo manage resources sustainably requires:• Planning for their depletion• Planning for their

replacement by less-damaging alternatives

What are some of the negative consequences of

using fossil fuels?

Humankind is faced with global challenges.How will we manage them?

Peak oil – We probably won’t run completely out of oil. But it is likely to get very expensive.Global warming – How quickly will warming proceed and what are some of the related consequences?Soil erosion – It is estimated that 65% of Earth’s soil has been degraded by erosion, desertification, and salinization.Fresh water – Around the world drought, pollution, and overuse threaten water resources.Economic minerals – Mineral resources are finite and increased demand can make some of them unaffordable.

Where does your drinking water come from, and what are the threats to its quality

and quantity?

Critical Thinking

• Is the use of reasoning to explain the world around us.

Any explanation for a process or a phenomenon must be testable.

• Inductive Reasoning (observations) used to formulate an hypothesis

• Principle of Parsimony used to select the most likely hypothesis

“The simplest explanation is often the correct one.”

• Deductive Reasoning generates testable predictions, based on the hypothesis

• These are unified under the Scientific Method

The Scientific Method

• The Scientific Method uses observations and experiments to build and refine hypotheses that explain phenomena.

Global challenges will be solved by critical thinkers with an enduring understanding of Earth

• Geology encompasses a vast range of time and space.

• Earth materials are recycled over and over again (Rock Cycle).

• Plate Tectonics controls the geology of Earth’s surface.

• Geologic systems are the product of interactions between the solid Earth, water, the atmosphere, and living organisms.

• Rocks and sediments are pages in the book of Earth’s history.

Sedimentary rocks in the Grand Canyon

The Theory of Plate Tectonics Is a Product of Critical Thinking

• PANGAEA – basis of Alfred Wegener’s Continental Drift Theory

• Harry Hess’s Theory of Seafloor Spreading provided a framework to understand the problem

Alfred Wegner’s continental drift hypothesis was never widely accepted because, although he was correct in observing that the continents had

moved, he had no credible hypothesis for “how” it happened.

Theory of Plate Tectonics

Theory of Plate Tectonics explains:

• Similarity of fossils and rock types across ocean basins• Chains of volcanic islands (Hot Spots)• Past existence of the supercontinent Pangaea

Many other geological phenomena are explained by Plate Tectonics. Can you name a few?

THE MODERN CONTINENTS EVOLVED

FROM PANGAEA THROUGH RIFTING AND

PLATE MOVEMENT

Continents Form Over Time

Rocks

• A Rock is a solid aggregation of minerals

• Each mineral in this rock has a different colour. They also have other distinctive properties such as hardness, cleavage and lustre.

Three families of rock

Form through geological processes that lead to their recycling through the rock cycle.

Igneous

Sedimentary

Metamorphic

How, for example, can an igneous rock be turned into a sedimentary rock?

Three ways to form rocks

Igneous

Sedimentary

Metamorphic

Geologists study dangerous natural processes known as Geologic Hazards

• Volcanic Eruptions

• Earthquakes and tsunami

• Mass wasting events (e.g., rock slides and debris flows)

• Major storms and their effects

Describe a geological hazard that has taken place in your region in the past year?

Natural Resources

• Natural Resources are materials that occur in nature and are essential or useful to humans. Most geological resources are non-renewable.

Principle of Uniformitarianism

• Earth is very old.• Natural process have

been uniform through time.

• The study of modern geologic processes is useful to our understanding of past geologic events

“The present is the key to the past”

Archaeopteryx is unique to the Jurassic Period, but the processes that lead to the fossilization of this individual 150 million years ago are similar to those happening in lakes today.

The Geologic Time Scale

• The Geologic Time Scale summarizes Earth’s History

• Time is divided into progressively shorter intervals defined by specific fossils and strata found in the geological record:

Eons Eras

Periods

Epochs

The Pleistocene Epoch is part of which Period, which Era and which Eon?

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