Chapter 14, Lesson 1 "The Rock Record"

Materials:

• Worksheet, "The Rock Record"

Objective:

• Students will defineg eologic time.
• Students will explain what a fossil is
• Students will describe three ways fossils form.

Anticipatory Set:* Show the student the imprints of three objects, two which are common and one which is not common. Ask the following questions of the students. Can you identify the objects that left there mark in the clay. Can you tell what they are used for? If you were a scientist uncovering these imprints what might it tell you about the people that lived in 2006?

Teacher Input:* Much of what we know about the earth's history is by studying similar fossils and fossil imprints. Most living things leave no trace when they die. Especially soft tissues are very rearly ever found. Most fossil are imprints or representations of the hard parts of an organism. What can you infer about these fossils' teeth? (herbivoure teeth fossil, carnivore teeth fossil) There are other things you can tell. Did this organism walk on two legs, four or did it fly from place to place? What is one thing that fossils do a very bad job of telling us?(behavior 1, behavior 2)

A year may seem like a long time when you look at it from a short term perspective. If we are speaking about the history of humans though a year is not nearly as long we start talking about decades, centuries or even millenium. Geologic time though is so long that a millenium is a very short period of time. Consider that the grand canyon is a very young river valley and it is 6 million years old. It is considered young because the earth is thought to be nearly 4.6 billion years old. See this animation of the Earth's History. The record of the earth has not been recorded in books or newspapers but we do find a good recording under our feet. In those rocks we can find traces or remains of orgnisms that died when that layer of rock was created. These remains are known as fossils. Because it is not easy for an organism to become a fossil, there may have been organisms alive a million years ago that left no trace in the rocks. WolfKill1, WolfKill2, Wolfkill3. In order for something to become a fossil it must be burried fairly quickly after it's death. This may occur in the sea floor, in a glacier, sandstorm, volcanic eruption, or avalanche.

Since fossils are a trace or remains of an organism it doesn't have to be the organism itself. There are several different kinds of fossils. An organism may be preserved through petrification. There is not organism left but the orginal parts have been replaced by minerals that filled the space where an organism decayed. An organism's imprint may also be a fossil. Again, there is no organism but the organisms shape has been left in a rock. This can be anything from the ouline of the body to just a footprint. It is known as a mold. If that mold fills in with solid minerals then you have a cast of the organism. Sometimes but rarely the actual tissues of the organism can be preserved. This has happend with wooly mamoths frozen in glaciers or permafrost, saber-toothed tigers have been found in tar pits, and insects have been found trapped in tree sap.

Guided Practice:* Students will take turns answering questions from page 337 which cover Lesson 1 of chapter 14.

Independent Practice:* Students will complete the worksheet, Chapter 14 Lesson 1, "The Rock Record"

Check for Understanding:* Students will take a quiz on lesson 1 of chapter 14.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-3 Students will understand models describing the composition, age, and size of our universe, galaxy, and solar system and understand that the universe is constantly moving and changing (Universe);
• SCI A-7 Students will understand how the earth changes because of plate tectonics, earthquakes, volcanoes, erosion and deposition, and living things (Processes that Shape the Earth);

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and:
• SCI A-16 Students willunderstand basic concepts about the theory of relativity, which changed the view of the universe by uniting matter and energy and by linking time with space (Relativity).