7th Grade Science

Unit 3: Earth's Age 

 

The study of Earth’s history enables people to use observations of present processes to infer past history of the Earth. The Grand Canyon’s undisturbed horizontal sedimentary rock layers allow for these inferences through the study of individual rock types, formations, sequences, and use of index fossils. The GrandCanyon allows us to use the relative geologic time scale to understand vast amounts of time and the changes that have taken place in Earth’s history.

 

Enduring Understandings:

Earth’s surface is constantly changing and its history can be studied through evidence of the changes.

Thousands of layers of sedimentary rock confirm the long history of the Earth. The youngest layers are not always found on top, because of folding, breaking, and uplift of layers.

 

 

Essential Questions?

How do scientists know what changes occurred long ago in and on Earth’s surface?

How are the relative ages of rocks measured?

How are the absolute ages of rocks measured?

 

 

 

Standards

SC.7.E.6.3 Identify current methods for measuring the age of Earth and its parts, including the law of superposition and radioactive dating.

SC.7.E.6.4 Explain and give examples of how physical evidence supports scientific theories that Earth has evolved over geologic time due to natural processes. 

 

 

Knowldege and Skills 

• Explain natural geologic processes that support the scientific theory of Earth’s evolution (ex: Grand Canyon).

• Uniformitarianism is the principle that the geological processes now are the same as geological processes of the past.

• The fossil record provides evidence of past life on earth and is used to infer such things as environmental conditions and the changing locations of Earth’s continents.

• Earth’s surface features, such as mountains and landforms, reveal Earth’s past.

• Geologists use the Law of Superposition for relative dating of the Earth.

• Sedimentary rock layers can be disturbed by folding and faulting.

• Fossils can be used to determine the relative ages of rock layers.

• Radioactive dating involves determining the proportion of radioactive atoms in a rock sample.

• Radioactive dating is used for absolute dating of the Earth’s material

• Give examples of scientific theories of geologic time.
• Identify and explain examples of natural geologic processes that support the scientific theory of Earth’s evolution (ex: Grand Canyon formation).
• Recognize difference between a theory and law.
• Explain the Law of Superposition including faulting and folding.
• Identify and describe current scientific methods for measuring the age of Earth and its part.