Changing Earth's Surface

In this lesson, students apply their knowledge of plate tectonics and the rock cycle to evaluate how scientists analyze geologic clues in rock, looking at rock properties and layers, as well as fossil evidence, to piece together how the landscape has changed over time, and which Earth processes were most likely responsible for those changes.  

• Different processes, including weathering and erosion, have the effect of reshaping and re-forming the matter that makes up different rocks in the rock cycle. The matter that makes up the rocks is never created or destroyed. Heat and pressure are constantly reshaping and re-forming the matter into new kinds of rocks with different properties.  
• Scientists classify rocks based on how they are formed. There are three categories of rock: sedimentary, metamorphic, and igneous.
• The processes that form sedimentary rock are the same as those that form fossils, so sedimentary rocks often hold fossils.
• Because of how fossils are formed, scientists can determine a fossil’s age based on where it is found relative to other fossils. Fossils that are found in lower layers of rock are more ancient than fossils found in higher layers.
• Scientists study the fossil record, which includes all of the fossils that have ever been found, to understand Earth’s history. Scientists have learned about major changes that Earth’s surface has undergone based on the locations of certain fossils.

• How do weathering and erosion contribute to the rock cycle?
• How does the rock cycle support the conservation of matter, which states that matter is never created or destroyed?
• How are both metamorphic rock and igneous rock different from sedimentary rock?
• How can rocks change from one form to another?
• How can sedimentary rocks tell scientists about past life on Earth?
• Why are fossils often found in sedimentary rock?  
• What evidence can you observe from the map that supports the idea that the continents were once joined?
• Why were scientists excited to discover fossils of an ancient fern in both South America and Africa?  
• How do scientists explain the movement of the continents?  
• Why is it useful for scientists to analyze fossils according to the location of where they are found?

Erosion: the transport of sediment by wind, water, or gravity

Fossil: the remains of ancient animals and plants, the traces or impressions of living things from past geologic ages, or the traces of their activities

Fossil record: all of the fossils that have ever been found, which scientists use to understand Earth’s history

Rock cycle: the processes that form, break down, and re- form rock from one category to another

Rocks: mixed mineral matter that makes up the surface of Earth and other terrestrial objects

Sediment: a collection of particles of rocks, minerals, and the remains of plants and animals

Weathering : the breakdown of rock into smaller pieces from exposure to wind, water, gravity, changes in temperature, and/or biological forces

For the hands-on activity in this lesson, students analyze geologic clues in a sample of quarry rock to explain how Earth’s landscape has changed over time. Students use their data charts, a world map and a model supercontinent to identify the kind of rock present in the quarry, the kinds of fossils found, and their locations. Students analyze this information to determine how Earth changes over time, and how scientists can piece together those changes by studying Earth’s materials and processes.