Earth’s Internal Structure & Rock Cycle

The following is a list of important words and concepts used in this lab module:

Asthenosphere

Extrusive igneous

Metamorphic rocks

Chemically precipitated sedimentary rocks

Geologic time scale

Organic sedimentary

Cinder cone volcanoes

Igneous rocks

Rock cycle

Clastic sedimentary

Intrusive igneous

Sedimentary rocks

Composite Volcanoes

Lithification

Seismic waves

Core

Lithosphere

Shield Volcanoes

Crust

Mantle

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

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INTRODUCTION

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

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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

C. Stratovolcanoes

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.

GLOBAL PERSPECTIVE

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?

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A. France

B. Greece

C. Italy

D. Germany

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?

A. Composite

B. Cinder cone

C. Shield

D. Crater

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?

A. Composite

B. Cinder cone

C. Shield

D. Crater

Uncheck the Nairobi folder. Double-click and select Philippines and SE Asia.

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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?

A. Composite

B. Cinder cone

C. Shield

D. Crater

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?

A. Composite

B. Cinder Cone

C. Shield

D. Crater

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Collapse and uncheck the GLOBAL PERSPECTIVES folder.

ROCK TYPES

As noted in the Introduction, all rocks can be classified as one of three basic rock types: igneous, sedimentary, or metamorphic.

Igneous rocks

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.

Intrusive formations

(in red)

Figure 1. Igneous intrusive formation (Arbogast 2nd Ed).

Expand the ROCK TYPES and Igneous Rocks folders.