Session #3: Lines of Evidence for Past Change


This session begins with a look at the nature of science, a review of energy transfer, transportation and deposition, and then explores stratigraphy, fossil evidence of past life, and evolution.

Jump to: Nature of Science | Reviewing Energy Transfer, Transportation and Deposition | Stratigraphy |Stories from the Fossil Record | The Importance of Variation | Looking at the Big Ideas | Additional Resources

Stressing the Nature of Science

Teachers continued the activity from Session #2, gathering further evidence, and revising hypotheses.

Reviewing Energy Transfer, Transportation and Deposition

Erosion is the process through which surfaces of rocks and soil are loosened and then transported elsewhere. But where does all of that sediment go? This series of slides illustrates the nature of San Francisco Bay as a depositional basin.

The San Fransisco Bay as an Energy Review

Stratigraphy - Timing Events in the Past

Geologists determine the sequence of geological events by using certain basic principles and assumptions. These slides discuss horizontality and superposition, cross-cutting relationships, inclusions, unconformities, and correlation in order to determine the sequence of events.

Timing Events in the Past

Stories from the Fossil Record

The fossil record provides concrete evidence of the history of life and the processes through which it has evolved. The clues are numerous and can be interpreted by comparing an entire assemblage of fossils, a single fossil, or even the traces left by past life.

  1. Stories told from a fossil assemblage

  2. Stories told by a single fossil

  3. Stories told by trace fossils
    Activity: Interpreting Tracks

The Importance of Variation

Variation exists among individuals within species. Variation leads to different "survival" rates, which leads to changes in frequencies in a population, which is evolution.

  1. Variation within a population

  2. Variation and Selection
    Activity: Candy Dish Selection

  3. Variation and Genetic Drift

Looking at the Big Ideas

Discussion: Identifying the evolution concepts

Additional Resources

Understanding Geologic Time: This web-based module introduces students to geologic time, the evidence for events in Earth's history, relative and absolute dating techniques, and the significance of the geologic time scale.

Getting Into the Fossil Record: This web-based module helps students gain a basic understanding of what a fossil is and how a fossil forms.

Stories from the Fossil Record: This web-based module provides students with a basic understanding of how fossils can be used to interpret the past. There are four different pathways to explore: biodiversity, geologic time, paleoecology and past lives.

How Big is a Billion? Most people have a difficult time comprehending the enormity of the numbers involved in discussions of geologic time. These exercises help students to better understand what "a billion" really means.

Updated January 5, 2003

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