Lab 02:Earth’s Internal Structure, Rock Cycle, & Geologic Time
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LAB MODULE 12: INTERNAL STRUCTURE OF THE EARTH
Note: Please refer to the GETTING STARTED lab module to learn tips on how to set up and maneuver through the Google Earth () component of this lab.
The following is a list of important words and concepts used in this lab module:
Chemically precipitated sedimentary rocks
Geologic time scale
Cinder cone volcanoes
LAB MODULE LEARNING OBJECTIVES
After successfully completing this module, you should be able to:
Recognize and interpret the spatial patterns of volcanoes and volcanic activity at the global scale
Identify and characterize different rock types
Define the process of lithification
Recognize and differentiate the various internal layers of the Earth
Distinguish and describe the different types of volcanoes
Outline and explain the rock cycle
Interpret the topographic profile of a landscape
In this lab module, you will examine some of the fundamental concepts and principles related to the internal structure of the Earth. Topics include rock types, the rock cycle, geologic time and volcanoes. While these topics may seem disparate, you will learn how they are inherently related.
The module starts with four opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts related to Earth’s internal structure. Some of the vignettes have animations, videos, or short articles that provide another perspective or visual explanation for the topic at hand. After reading each vignette and associated links, answer the following questions. Please note that some components of this lab may take a while to download or open, especially if you have a slow internet connection.
Expand INTERNAL STRUCTURE, and then expand the INTRODUCTION folder. Double-click Topic 1: The Earth’s Internal Composition.
Read Topic 1: The Earth’s Internal Composition
Question 1: What is the depth of the Kola borehole as a percentage of the Earth’s radius? Calculate using the following equation:
A. (123km / 637km) * 100 = 19.3%
B. (123km / 6370km) * 100 = 1.93%
C. (12.3km / 637km) * 100 = 1.93%
D. (12.3km / 6370km) * 100 = 0.193%
Read Topic 2: Rock Types
Question 2: What are alternative terms used in place of “extrusive” and “intrusive” igneous rock?
A. Magma and granite
B. Pumice and lava
C. Volcanic and plutonic
D. Vesicular and plutonic
Read Topic 3: Geologic Time
Question 3: During the Devonian Period, where is North America located relative to the Equator? (Hint: Go to “Close-up: Phanerozoic Eon,” then click on Devonian in the time scale image)
A. Predominately east of the equator
B. Predominately west of the equator
C. Predominately north of the equator
D. Predominately south of the equator
Read Topic 4: Volcanoes
Question 4: The Hawaiian Islands are composed of linear chains of which of these types of volcano?
A. Cinder cones
B. Shield volcanoes
D. Lava domes
For the rest of this module, you will identify and explain the geographic distribution, patterns, and processes associated with Earth’s internal structure. In doing so, you will recognize and appreciate the impact the interior of the Earth has on the surface.
Collapse and uncheck the INTRODUCTION folder.
Volcanoes are not randomly distributed across the globe; rather, their locations are distinct (commonly located on plate boundaries) and these patterns are evident at regional to global scales. Despite the potential dangers associated with volcanoes, many cities are located near areas susceptible to volcanic activity. In this section you will describe the spatial patterns of volcanoes and volcanic activity, and identify volcanoes located near populous cites.
Expand the GLOBAL PERSPECTIVE folder. Double-click and select the Mediterranean and W Asia folder.
Question 5: Where will you find the majority of volcanoes in Europe?
Uncheck the Mediterranean and W Asia folder. Double-click and select Catania. Next, click on the Etna symbol in the Google Earth Viewer. Read about Mount Etna, located adjacent to the city of Catania on the Island of Sicily. To close the Smithsonian write-up on this volcano, click the X in the top right corner of the window.
Question 6: What type of volcano is Mount Etna?
B. Cinder cone
Uncheck the Catania folder. Double-click and select the Africa and Red Sea folder.
Question 7: Describe the general spatial pattern of volcanoes found on the continent of Africa (Hint: You might have to zoom in and out to view the spatial patterns of the volcanoes).
A. The volcanoes appear randomly distributed over most of Africa
B. Many are found along the Great African Rift valley located in eastern Africa
C. Many volcanoes form national borders of western and southern African countries
D. The majority are found within the Sahara Desert region located in northern Africa
Uncheck the Africa and Red Sea folder. Double-click and select Nairobi. Next, click on the Suswa symbol in the Google Earth Viewer. Read about Suswa, located west of the city of Nairobi, Kenya.
Question 8: What type of volcano is Suswa?
B. Cinder cone
Uncheck the Nairobi folder. Double-click and select Philippines and SE Asia.
Question 9: Describe the general spatial pattern of volcanoes found in this region (Hint: You might have to zoom in and out to view the spatial patterns of the volcanoes).
A. The volcanoes appear randomly distributed over most of SE Asia
B. Many are found along the margins of this region
C. Many volcanoes form national borders among the island countries
D. The majority are found on the island of Borneo and are evenly spaced apart
Uncheck the Philippines and SE Asia folder. Double-click and select Jakarta. Next, click on the Pulosari, Perbakti-Gagak and Salak symbols in the Google Earth Viewer. Read about these volcanoes, located south of the city of Jakarta, Indonesia.
Question 10: What type of volcanoes are these?
B. Cinder cone
Uncheck the Jakarta folder. Double-click and select Hawaii and Pacific Ocean.
Question 11: Describe the general spatial pattern of volcanoes found in this region (Hint: You might have to zoom in and out to best view the spatial patterns of the volcanoes).
A. The volcanoes appear randomly distributed over most of the Pacific Ocean
B. Many are found along the margins of this region and near islands or island chains like Hawaii
C. Many volcanoes form national borders among the island countries
D. There are few volcanoes in the Pacific; as a result, there are no apparent trends regarding their spatial patterns
Uncheck the Hawaii and Pacific Ocean folder. Double-click and select Hawaii. Next, click on the Mauna Loa symbol in the Google Earth Viewer. Read about this volcano, located southwest of the city of Hilo, Hawai’I, USA.
Question 12: What type of volcano is Mauna Loa?
B. Cinder Cone
Collapse and uncheck the GLOBAL PERSPECTIVES folder.
As noted in the Introduction, all rocks can be classified as one of three basic rock types: igneous, sedimentary, or metamorphic.
Igneous rocks are further divided into extrusive igneous rock and intrusive igneous rock.
Extrusive igneous rock is formed (cooled) on the Earth’s surface.
Intrusive igneous rock is formed (cooled) in the Earth. Unless there has been significant erosion of surface material, intrusive igneous rock are not easily detectable on the surface (Figure 1).
Some intrusive igneous formations include:
o Dikes – vertical intrusive rock that formed from cooled magma within fissures that cut across older rock. Dikes frequently differ in composition to the surrounding bedrock.
o Sills – intrusive rocks formed in horizontal fissures. Sills are often situated between older layers of sedimentary rock.
o Batholith – a large pluton, or mass of rock that cooled and solidified deep within the Earth. Some batholiths are several hundred miles long.
Figure 1. Igneous intrusive formation (Arbogast 2nd Ed).
Expand the ROCK TYPES and Igneous Rocks folders.
Igneous rocks – Shiprock, NM
Double-click and expand the Shiprock, NM folder.
This feature is the remnant of a throat of a volcano, with radiating dikes. This volcano erupted over 27 million years ago.
Double-click the Ship Rock Tour link to view an animation.
Click Photo 1 for a different view.
Uncheck the Shiprock, NM folder.
Igneous rocks – Stone Mountain, GA
Double-click the Stone Mountain, GA folder.
This is a large pluton near Atlanta, GA that was formed during the Devonian period in the Paleozoic Era.
Double click the Stone Mountain Tour link to view an animation.
Click Photo 2 for a different view.
Uncheck the Stone Mountain, GA folder.
Igneous rocks – Krafla, Iceland
Double-click the Krafla, Iceland folder.
The dark areas are a lava flow from the Krafla volcano in Northern Iceland. The lava cooled formed basalt and rhyolite, which are extrusive igneous rocks.
Double click the Krafla Tour link to view an animation.
Click Photo 3 for a different view.
Uncheck the Krafla, Iceland folder.
Question 13: What is the difference between the two types of igneous rocks?
A. The ages of the rocks. Intrusive rocks are always older
B. Extrusive rocks were formed in water, intrusive rocks were not
C. Intrusive rocks were formed in water, extrusive rocks were not
D. Intrusive rocks were formed in the Earth, extrusive rocks were not
Sedimentary rocks are formed by the deposition of sediments (usually in a marine environment) that under pressure slowly turn into rock. Lithification (cementing of sediment into rock) is an important process in the formation of this type of rock.
There are three board types of sedimentary rock: organic, clastic, and chemical precipitation.
Organic sedimentary rocks are formed from the deposition of carbon based material. Subjected to pressure, this material, over time, can form coal.
Clastic sedimentary rocks are sedimentary rocks composed of clasts or pieces of weathered and eroded rocks. They are classified by grain size and range from fine grained claystone (Figure 2) to coarse grained conglomerate (Figure 3).
Figure 2. Claystone (Wikipedia).
Figure 3. Conglomerate (Wikimedia).
Chemically precipitated sedimentary rocks are formed through the precipitation of calcium carbonate which is then deposited on the ocean floor. Over time, enough pressure can built such that lithification occurs creating this type of sedimentary rock. Limestone is a common example of a chemical precipitated sedimentary rock.
Expand the Sedimentary Rocks folder.
Sedimentary rocks – West Virginia
Double-click the West Virginia folder.
This is a coal mine in West Virginia, where mountain top removal is a common way of mining this sedimentary rock. Coal is an economically important sedimentary rock worldwide as nearly 40 percent of the electricity generated comes from coal power plants (Worldcoal, 2006).
Click Photo 4 for a different view.
Uncheck the West Virginia folder.
Sedimentary rocks – Grand Canyon
Double-click the Grand Canyon, AZ folder.
The Grand Canyon is a showcase of clastic sedimentary rock. Erosion by the Colorado River, coupled with tectonic uplift, has exposed layers of different types of largely sedimentary rock dating back nearly 2 billion years to the Proterozoic period in the late Precambrian Era.
Click the Grand Canyon Rock Layers folder to see an illustration of a cross section of the Grand Canyon.
Question 14: Why are there no rock layers younger than the Kaibab formation?
A. All the rock layers are younger than the Kaibab formation
B. The Kaibab formation was the last layer to be deposited
C. The Colorado River eroded younger layers
D. The Great Unconformity is younger
Click Photo 5 to see various rock layers in the Grand Canyon.
Uncheck the Grand Canyon, AZ folder.
Sedimentary rocks – Rocky Mountains
Double-click the Rocky Mountains folder.
The Rocky Mountains in Canada are comprised primarily of limestone and shale, suggesting at one time this area was once covered by an ocean. Scientists estimate this limestone was created during the Paleozoic Era (350 million years ago), and that uplift to create the mountains began during the last half of the Mesozoic Era (180 million years ago) (Gadd, 2008).
Click Photo 6 to see various rock layers in the Rocky Mountains.
Question 15: Which type of sedimentary rock (organic, clastic or chemical precipitated) is present in this photo?
D. Chemically precipitated
Question 16: Describe why the process of lithification is important in the formation of sedimentary rocks.
A. It binds sediments into a solid mass through compaction
B. It adds a lithium which chemically binds the sediments into a rock
C. Lithification does not play a part in the formation of sedimentary rocks
D. Lithification only plays a roles with clastic sedimentary rock formation
Uncheck the Rocky Mountains folder.
Figure 4. Gneiss, foliated (Wikimedia).
Metamorphic rocks are formed from igneous or sedimentary rocks that have been subjected to heat and pressure; in other words, the heat and pressure results in the rearrangement or recrystallization of minerals to form different minerals.
Metamorphic rocks formed from igneous rocks are sometimes called meta-igneous. Likewise, meta-sedimentary rocks are metamorphic rocks formed from sedimentary rocks.
Common metamorphic rocks include marble (from limestone) and gneiss (usually from granite).
Metamorphic rocks are divided into two broad categories, foliated and non-foliated:
Foliated metamorphic rocks (Figure 3) exhibit banding as the minerals present align to form bands.
Non-foliated rocks (Figure 4) lack this banding.
Metamorphoses can occur in two ways, namely contact metamorphism and regional metamorphism. The former happens over a small area and entails magma coming in direct contact with rock. The heat from the magma alters the crystal structure of the rock. The latter occurs over a much larger area and entails high heat and great pressure altering rock.
Expand the Metamorphic Rocks folder.
Metamorphic rocks – Jeff Davis Peak
Double-click and select the Jeff Davis Peak folder.
This is Jeff Davis peak which is comprised primarily of quartzite, a metamorphic rock formed from sandstone.
Double-click the Jeff Davis Peak Tour link to view an animation.
Click Photo 7 to see various rock layers of quartzite.
Uncheck the Jeff Davis Peak folder.
Figure 5. Marble, non-foliated (Wikimedia).
Metamorphic rocks – Carrara, Italy
Double-click and select the Carrara Italy folder.
The white areas are marble quarries near Carrara, Italy, not far from Pisa. The area is well known for Carrara marble which is found in the surrounding mountains. This marble is used for statues and buildings such as the Pantheon in Rome.
Click Photo 8 to see a Carrara marble quarry.
Question 17: Why is contact metamorphism restricted to a small area?
A. Because the body of protruding lava which causes contact metamorphism is relatively small in size
B. Because the body of protruding magma causes contact metamorphism is relatively small in size
C. Because only certain rocks can be metamorphosed and they are generally found in small quantities
D. Because all metamorphoses are restricted to small areas
Collapse and Uncheck the ROCK TYPES folder.
By interpreting seismic waves from earthquakes, scientists have divided the Earth’s interior into three major sections: core, mantle, and crust.
Click Earth’s Interior and use the illustration to identify the layers in the table below. Select the correct answer from the list provided below.
Iron & Nickel
Iron, Magnesium & Silicon
A. Lower Mantle
B. Outer core
C. Inner core
E. Upper mantle
Question 22: Explain how the structure of rock changes as you go from the lithosphere through the asthenosphere and upper mantle.
A. Solid rock, semi-solid rock, molten rock
B. Solid rock, molten rock, semi-solid rock
C. Semi-solid rock, molten rock, solid rock
D. Molten rock, solid rock, semi-solid rock
Collapse and Uncheck EARTH’S INTERIOR.
Volcanoes are divided into three types: cinder cone, composite, (or stratovolcano) and shield. These classifications are based largely on whether the eruption is fluid or explosive in nature.
Expand the VOLCANOES folder. Double-click the Capulin Mountain Tour link to view an animation.
This is Capulin Mountain in New Mexico. It is a cinder cone volcano. Cinder cone volcanoes are the smallest of the three types of volcanoes and are characterized by steep sides.
Double click and check the Folsom, NM box.
Double-click and select Folsom, NM.
Question 23: What is the contour interval of this map?
B. 20 meters
C. 20 feet
Question 24: Based on the contour lines, what is the highest elevation on this volcano?
A. 8,000 feet
B. 8,128 feet
C. 8,182 feet
D. 8,218 feet
Question 25: Based on the contour lines, what is the elevation in the center of the crater?
A. 7,800 feet
B. 7,775 feet
C. 8,125 feet
D. 7,900 feet
Uncheck Folsom, NM and then check Profile #1.
Right-click Profile #1 and then select Show Elevation Profile.
Question 26: What is the diameter of the volcano in miles?
A. 0.75 miles
B. 0.39 miles
C. 0.93 miles
D. 2.1 miles
Question 27: What is the average slope of the profile line?
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