Unit 6 Lesson 3 Scientific Theories

Age of Earth

• Earth is approximately 4.6 billion years old; oldest rocks are about 4 billion years due to destruction during formation.

Marine Fossils in Himalayas

• Marine fossils found in mountains suggest plate tectonics.

Theory of Continental Drift

• Alfred Wegener proposed that all continents were once connected as Pangea.

Evolution of Scientific Knowledge

• Scientific understanding evolves with technology and new evidence.

Differences Between Theories and Laws

• Scientific laws describe consistent phenomena; theories explain why events occur and can adapt.

Plate Tectonics Theory

• Describes Earth's lithosphere as segmented into moving plates.

• A) Theories can change based on new evidence, while laws describe fixed relationships.

Scientific Hypothesis and Theory

• A hypothesis is a testable prediction; a theory is an accepted hypothesis within the scientific community.

Response to New Evidence

• New evidence can challenge and provoke changes in existing theories.

Half-Life Activity

• Half-life is the time for half of a radioactive substance to decay (e.g., Carbon-14's half-life

Summary

The Earth is approximately 4.6 billion years old, with some rocks lost during its formation. Alfred Wegener's Theory of Continental Drift posits that continents once formed a supercontinent, Pangea, before drifting apart. Scientific theories evolve with new evidence, while laws describe consistent natural phenomena.