Module #8 - Internal Structures of the Earth
INSTRUCTIONS FOR TODAY
1. Watch the following videos.
a. Video of the Day: LeBron James compares the Earth's History to a basketball game ( 8 minutes) - Review from Geological Time.
b. Video of the Day: Khan Academy: Structure of the Earth (8 minutes)
Be sure to make point form notes in your digital video journal. Please make sure that you SHARE your document with Mr. Durk.
2. Read the following information below in Part 1: Background and Terminology. Follow all hyper-links (BLUE) to external websites for activities, demonstrations and videos (if applicable). Copy only KEY information (i.e. the highlighted terms) to your digital notebook (in google docs).
3. Complete Part 2: Webquest Activity (see below)
DUE DATE: Before Module #9 - Tues. April 5th
Part 1: Background and Terminology
Please remember to record all definitions and content in your virtual notebook. Definitions can be found by clicking on highlighted words.
Earth’s Layers
The earth is approximately 12,750 kilometres (km) in diameter. Our planet is made up of three main layers: crust,mantle , and core . The crust, the outermost layer, is rigid and very thin compared to the other two. Beneath the oceans, the crust varies little in thickness, generally extending only to about 5 km. The thickness of the crust beneath continents is much more variable, but averages about 30 km; under large mountain ranges, such as the Alps or the Sierra Nevada, however, the base of the crust can be as deep as 100 km.
Below the crust is the mantle, a dense, hot layer of semi-solid rock approximately 2,900 km thick. The mantle, which contains more iron, magnesium, and calcium than the crust, is hotter and denser because temperature and pressure inside the earth increase with depth. At the center of the earth lies the core, which is nearly twice as dense as the mantle because its composition is metallic (iron-nickel alloy) rather than stony. The earth's core is made up of two distinct parts: a 2,200 km thick liquid outer core and a 1,250 km thick solid inner core. As the earth rotates, the liquid outer core spins, creating the earth's magnetic field.
Source: www.coolgeography.co.uk
Click on the animated model of Earth’s internal structure to learn more about Earth’s layers.
Determining Earth’s Layers
Seismology has become the principle method used in studying Earth's interior. Seismology on Earth deals with the study of vibrations that are produced by earthquakes, the impact of meteorites, or artificial means such as explosions. On these occasions, a seismograph is used to measure and record the actual movements and vibrations of the ground and within the earth.
Scientists categorize seismic waves or movements into four types of diagnostic waves that travel at speeds ranging from 3 to 15 kilometres per second. Two of the waves travel around the surface of the earth in rolling swells. The other two, Primary (P) or compression waves and Secondary (S) or shear waves, penetrate the interior of the earth. Primary waves compress and dilate the matter they travel through (either rock or liquid) similarly to sound waves. They also have the ability to move twice as fast as S waves. Secondary waves propagate through rock but are not able to travel through liquid. Both P and S waves refract or reflect at points where layers of differing physical properties meet. They also reduce speed when moving through hotter material. These changes in direction and velocity are the means of locating discontinuities.
Seismic discontinuities aid in distinguishing divisions of the earth into inner core, outer core, lower mantle, upper mantle, asthenosphere, moho, and crust (oceanic and continental).
Resources
Part 2: Teaching About the Structure of the Earth - A Webquest Activity
Using a variety of interactive websites and simulations you will create a "webquest activity" geared towards students in grades 6-8. You will create an online activity that includes a series of animations, videos and online activities for younger students to learn about the Geologic Structure of the Earth and the different layers of the Earth.
Create your document using google docs and include multiple choice questions, fill-in-the blanks and other types of questions for the students to test their understanding as they go. Include graphics / images on your document to supplement the text information. Your student worksheets should be detailed and structured clearly. (minimum of 2 pages in length, include the website url's and the webquest name near the top of your 1st page). You should have a minimum of 15 questions that student would have to answer as they complete the activity. Please include a 2nd copy with all of the answers included as the "Teacher's Copy". Your webquest can be a website (google site) or a google document.
Here are some examples of "Webquests" that I quickly found online that will provide a examples of formats that you could follow (there are numerous examples online)
Submit your "webquest" activity to Mr. Durk via Google Share before Module #9