6 th Grade PSI Earth's Materials and Systems Part I : The History - - PDF document
Slide 1 / 75 Slide 2 / 75 6 th Grade PSI Earth's Materials and Systems Part I : The History of Planet Earth www.njctl.org Slide 3 / 75 Table of Contents: The History of Planet Earth Click on the topic to go to that section Earth's Layers
· Earth's Layers · Three Types of Rocks · Rock Strata · Early Life on Earth / Fossils
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Earth is a "terrestrial" or rocky
up of rocks and minerals. The rocks and minerals that now make up our Earth were once just small chunks revolving around our
combined to form the planet we live
What are the other rocky planets in our solar system?
Our Earth is divided into four major layers: Crust Mantle Outer Core Inner Core
Think of the crust of Earth as the crust of a pizza pie. The crust is the outermost layer of Earth, just like the crust above is the outermost layer of the pizza!
This section is very thin compared to
25 miles thick) and it is very hard and rigid. The crust is composed of plates that slide around on top of the section below it. This portion is called the lithosphere. There are 2 parts to the crust. One is the land. What is the other part?
The next layer down is the mantle. This is the largest layer - about 1,800 miles thick! The mantle is made up of incredibly hot, semisolid rock (basically think of rock in a form sort of like pudding). This layer makes up about 2/3 of Earth's mass.
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The Outer Core is so hot that it is entirely
It is made up of mainly nickel and iron. To give you an idea of how hot it is, nickel becomes a liquid at 2,650 degrees F and iron melts at 2,800 degrees F! What temperature does ice melt at?
At the very center of Earth, you will find the Inner Core. Like the Outer Core, this layer is also extremely hot and is made of nickel and iron. Although the temperature is higher, the nickel and iron here are in solid form because of the intense pressure that this layer experiences.
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The layers of Earth are constantly moving and changing due to intense heat and pressure. The energy of this heat and pressure results in the formation of rocks. But what exactly is a rock? With your table, come up with some characteristics
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How a rock forms depends on what type of rock it is. There are three types of rocks: Sedimentary Metamorphic Igneous Click on the rock type to see an example.
Metamorphic rock forms when another type of rock changes its chemical makeup because
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bacteria
The first cells that existed on Earth were closely related to
Most prokaryotes are single-celled organisms. Why were the first
very simple? What is a more common name for prokaryotes? Move the image once you come up with an idea.
Very specific conditions were needed for these living organisms to form. Organic chemicals (chemicals that include carbon) as well as some sort of heat were needed to form these cells.
Fossils are typically found in Sedimentary Rock
A fossil is the preserved remains of an organism which is found in rock formations. In what type of rock do you think fossils usually can be found ? Think about how rocks are formed. The answer is under the photo to the right
Photo : Thomas Bresson Fossilized Seaweed
As was mentioned in the section on the Types of Rocks, the older rocks will be further down within Earth. Fossilized organisms will be about the same age as the layer of rock they are found in. It is the job of a paleontologist to excavate, or dig up, these fossils and determine their ages.
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The work of a paleontologist is very delicate and difficult. It requires a lot of patience and care. In this activity, you will practice these skills on different types of cookies. Can you excavate the chocolate chips from the cookies using only your paleontology tools?
Now that the "fossils" have been excavated, how do they get from the site to the museum? Use the site above to track a vertebrate fossil!
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Scientists use various techniques to determine the age of rocks. Sometimes, scientists are able to determine the absolute age, or the exact age, of a rock or fossil. The absolute age of the petrified wood above is 2,500 years old.
Scientists use a technique called radiometric dating to determine absolute age. Radiometric dating compares the ratio of a radioactive element with the amount that has decayed in the rock or fossil.
When it comes to relative age, scientists analyze the amount of certain radioactive elements within the object. They then use the "half life" of the element to determine the object's age. The half life is the period of time it takes for half of the substance to decay.
A radioactive version of the element Carbon is known as Carbon 14 because it has an atomic mass of 14 (rather than the usual 12). What is atomic mass? Carbon 14 has a half life
Carbon 14 is found in every living thing.
This means that if there are 100 atoms of Carbon 14 in the tree when it was alive, there will be only 50 left after it has been dead for 5,700 years. So after one half life, the amount
half.
In organisms that were once living, the amount of Carbon 14 will be cut in half every 5,700 years. Scientists use this information to determine how long an organism has been dead ... and therefore find out roughly how old it is!
In this activity, you will learn about different types of radiometric dating, such as carbon dating. You will understand how decay and half life work to enable this dating. You will finish it up with a game that tests your ability to match the percentage of the dating element that remains to the age of the object!
When scientists cannot be exact, they try to determine an object's relative age. This is when they compare the age of an object or event to another object or event. Scientists can estimate the age of this volcano by looking at rocks and fossils found around its base. Why would they use the base of the volcano and not the top?
What is an index fossil? Click on the dinosaur below to uncover the definition! An index fossil is used to determine the age range of a rock layer. It is the fossil of an organism that existed only for a limited period of time. Since scientists know that the stegosaurus lived between 150 and 155 million years ago, any rock layer containing a stegosaurus fossil will be around that age as well.
When new rock is formed on the surface of Earth, it settles on top of what was there before it. The deeper you dig into Earth's surface, the farther back in time you will see.
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Permission Granted: FL Museum of Natural History