Science - 2017-18

ES.9 - Earth's History

The student will investigate and understand that many aspects of the history and evolution of Earth and life can be inferred by studying rocks and fossils. Key concepts include
a) traces and remains of ancient, often extinct, life are preserved by various means in many sedimentary rocks;
b) superposition, cross-cutting relationships, index fossils, and radioactive decay are methods of dating bodies of rock;
c) absolute and relative dating have different applications but can be used together to determine the age of rocks and structures; and
d) rocks and fossils from many different geologic periods and epochs are found in Virginia.

Bloom's Levels:  Analyze; Understand

Adopted: 2010


  • Physical evidence, such as fossils and radioisotopic dating, provide evidence for the Earth system's evolution and development.

  • I can explain how modern animals are related to extinct species.
  • I can determine the age of an object.
  • I can use the age of objects to determine how old certain geographic features are.


  • The history of Earth and the ages of rocks can be investigated and understood by studying rocks and fossils.
  • Evidence of ancient, often extinct life is preserved in many sedimentary rocks. A fossil is the remains, impression, or other evidence preserved in rock of the former existence of life. Fossil evidence indicates that life forms have changed and become more complex over geologic time. Some ways in which fossils can be preserved are molds, casts, and original bone or shell. 
  • Relative time places events in a sequence without assigning any numerical ages. Fossils, superposition, and cross-cutting relations are used to determine the relative ages of rocks. Absolute time places a numerical age on an event. Radioactive decay is used to determine the absolute age of rocks. 
  • The age of Earth is about 4.6 billion years.
  • In Virginia, fossils are found mainly in the Coastal Plain, Valley and Ridge, and Appalachian Plateau provinces. Most Virginia fossils are of marine organisms. This indicates that large areas of the state have been periodically covered by seawater. 
  • Paleozoic, Mesozoic, and Cenozoic fossils are found in Virginia. 


In order to meet this standard, it is expected that students will

a)  describe how life has changed and become more complex over geologic time.

     analyze the impact and role of global catastrophies (including asteroid/comet impacts, volcanism, continental collisions, climate collapse) on extinctions and evolution. 

b)  interpret a simple geologic history diagram, using superposition and crosscutting relations.

     analyze how radioactive decay provides a reliable method to determine the age of many types of organic and inorganic materials. 

     analyze and interpret complex cross sections using both relative and absolute dating to unravel and define the geologic history of  the section.


Mesozoic era, hydroelectric energy, half-life, solar energy, relative age, permineralized remains, Precambrian time, radioactive decay, fossils, Paleozoic era, carbon film, principle of superposition, oil, cast, fossil fuel, geologic time scale, Cenozoic era, geothermal energy, mold, absolute age, index fossils, eon, epoch

Updated: Nov 28, 2017