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Stratigraphy and Evolution: Using Fossils to Tell "Deep Time"


The view of time related to the universe, Earth and humanity has changed throughout human history, depending on the various data available, and the social and religious beliefs of the time. In the eighteenth century, the intellectual climate of rationalism allowed educated individuals, like Scottish physician James Hutton, to recognize the cyclical nature of geologic processes and thus grasp the concept of deep time. Geologists estimate the Earth is 4.6 billion years old. This span of time has been subdivided and the units arranged into a geologic time scale. The study of historical geology, the rocks and fossils associated with the Earth’s history, present the student with the nature of time within a geologic context.

Through this activity students will learn about the earliest concepts of telling time in rocks using fossils: relative age dating using the various flora and fauna present. This allows for the construction of a relative geologic time scale, namely, one that is not tied to absolute ages. An exploration of Sir Charles Lyell’s early application of relative age dating and his influence on Darwin’s theory of evolution as developed on The Beagle will be included. The concept of “deep time” will be explored through the fossil record of the earliest forms of life.