Microsoft Word - GEOG1106_Lab8_EarthInterior&RockCycle.docx
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Earth Interior and the Rock Cycle Lab Questions
***Please submit only this document at the end of the lab period***
INSTRUCTIONS: Please read the lab reader before beginning this exercise. The following lab questions will be based upon the material given in the lab reader.
Part I: Exploring the Earth’s Spheres
1. [10] Provide an example (write a short but meaningful paragraph) of how atmosphere and hydrosphere relate.
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2. [10] Provide an example (short, meaningful paragraph) of how atmosphere and lithosphere relate.
Part II: The Life Cycle of a Rock
3. [5] A rock is defined as:
4. [5] A mineral is defined as:
5. [5] Would coal, a material that comes from decayed plant matter, be considered a mineral? Why or why not?
6. [10] Name the three rock types and describe how they differ from each other.
7. [10] What are two ways that a metamorphic rock may form? (hint look at Figures 3 and 4 of the reader)
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8. [30] Open earth.google.com/web, activate the photos option and use the magnifying glass (search option) to copy and paste the coordinates below. Once you find the place, look at the posted photos nea
y the site and annotate the city and state, what type of rocks are at each given location and how that type of rock forms (hint: look at the reader’s section describing the rocks at El Paso).
XXXXXXXXXX, XXXXXXXXXX
XXXXXXXXXX, XXXXXXXXXX
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XXXXXXXXXX, XXXXXXXXXX
Part III: The Earth’s Interio
9. [5] List and describe the two ways that earth scientists investigate the structure of the earth.
10. [10] What are the three main layers of the earth called and what makes them unique?
Microsoft Word - GEOG1106_Lab8_EarthInterior&RockCycle_Reader.docx
Reader:
Earth Interior and the Rock Cycle
Learning Outcomes: This laboratory has the overall objective of exploring the earth's interior and understanding the rock cycle whilst laying the foundations for the following lab in plate tectonics. After finishing this exercise, students should be able to discuss the variety of rocks exposed at the surface of the earth, how they are formed and weathered, and to have an understanding of the interior layers of the earth. The specific learning outcomes are:
1. Describe the four distinct and connected realms of earth study.
2. Draw and describe the "life cycle" of a rock, including the basic processes that drive it.
3. Define the earth and describe its layers and composition.
4. Discuss which tools scientists use to inte
ogate the subsurface and the strengths and weaknesses them.
Materials: Pencil, colored pencils, lab handout, google earth.
Part I. Exploring the Earth’s Spheres
So far, in this lab, we have explored a wide range of topics related to the physical processes of the Earth. We can group these topics into four different categories or "Spheres."
The first is the Atmosphere, which encompasses the body of gasses that su
ounds our planet and are held in place by earth's gravity. In our labs, we have studied atmospheric circulation, stability, air masses and weather in addition to other topics related to the atmosphere.
We have also explored the Hydrosphere, which comprises of all of the water on or near the planet's surface. This includes all of the observable bodies of water at the surface of the earth, all of the groundwater and water beneath the surface, and all of the moisture in the atmosphere. We've explored concepts
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of air moisture, precipitation, and water budget in this lab, all topics that relate to the hydrosphere.
The Biosphere includes all of the living organisms on our planet. This spans all of the life observable at the surface, in the oceans, and in the air, ranging from the largest mammals to the tiniest microorganisms.
In this lab we will begin to explore the Geosphere, which is made up of all the rocks and minerals of the earth. This includes molten rock, heavy metals, and all of the abiotic parts of soils and biologic remains that may become fossilized over geologic time. To explore the geosphere in this lab, we will start with what we can observe at the surface and then learn about what scientists can see in the subsurface.
Part II. The Rock Cycle
What is a Rock and what are Minerals?
A rock is any naturally occu
ing solid made up of minerals or mineraloids. Rocks form the Earth's outer solid layer and most of its interior. They are generally classified into three types: Igneous, Metamorphic, and Sedimentary rocks.
Minerals and Mineraloids are the building blocks of rocks. Geologists define minerals as naturally occu
ing, inorganic solids that have a definite chemical composition and repeating, ordered internal chemical (crystalline) structure. Examples of minerals that we commonly use are halite (table salt), copper (found on its own in nature or as parts of other minerals like malachite), and many more. Just as they are the building blocks of rocks, minerals and the properties they have are also the building blocks of many everyday items that we use or consume. Mineraloids are mineral-like substances that do not demonstrate a crystal structure. Obsidian or "volcanic glass" is a common example of a mineraloid.
Minerals and mineraloids form rocks either by chemically precipitating and bonding together as molten rock cools to solid rock (igneous and
metamorphic rocks), or by being cemented together as grains (sedimentary rocks). Figure 2 illustrates some examples of minerals and mineraloids.
The Three Rock Types Igneous Rocks
Igneous rocks are formed by the cooling and solidification of magma (molten rock in the subsurface) or lava (molten rock at the surface). They occur in a wide variety of textures and compositions relating to their mineralogical makeup, process of formation, and rate of cooling. Igneous rocks with mineral components big enough to see with the naked eye (Phaneritic igneous rocks) tend to occur when magma cools slowly whereas igneous rocks whose mineral components are too small to see with the naked eye (Aphanitic igneous rocks) tend to occur when lava cools rapidly at the surface. These rocks can also be considered intrusive when they formed solid rock in the subsurface, and extrusive when they form from lava cooling at the surface. Intrusive rocks are abundant in the subsurface and make up the cores of our continents. Extrusive rocks are widespread and are related to volcanic activity. Figure 2 illustrates some examples of Igneous rocks.
Sedimentary Rocks
Sedimentary rocks are formed from the deposition of mineral or organic particles which are then cemented together by another mineral. They can be classified in two
oad categories: Clastic sedimentary rocks and Biochemical sedimentary rocks. Clastic rocks are made of rock fragments that have been cemented together. Their constituents come from the
eak down (erosion and weathering) of other rocks, including other sedimentary rocks, into smaller particles and rock fragments called sediment. Once formed, sediment is transported via wind (eolian), water (marine and fluvial), glacial and gravity related processes. Once the particles are deposited (no longer transported), they can be turned into rock through a process known as lithification, turning them into sandstones, conglomerates, mudrocks and
eccias. Biochemical sedimentary rocks are comprised of the skeletal remains of animals that use materials dissolved in air or water to build themselves. Limestones are formed from the skeletons of marine organisms like coral, mollusks, and tiny foraminifera. Coal is formed from the organic matter left by plants. Chert deposits may form from the accumulation of microscopic organisms that precipitated silica. Figure 2 illustrates some examples of Sedimentary rocks.
Figure 2. Examples of Igneous, Sedimentary and Metamorphic rocks and minerals.
Metamorphic Rocks
Metamorphic rocks form when existing rocks are "baked" at elevated temperatures and pressures. After about 300 – 400 F rocks become hot enough to recrystallize and reorganize, forming distinctive minerals and textures that can be used to interpret the protolith (parent rock) and temperature and pressure processes and conditions that were involved in its metamorphosis. Garnet is an example of a mineral that crystallizes during metamorphosis. It is used to interpret that a rock bearing garnet has gone through intermediate to high levels of metamorphism. Figure 2 illustrates some examples of Metamorphic rocks.
The Cycle of Rocks
The rock cycle is a continuous process that recycles earth's material as illustrated by Figure 3.
Figure 3. A schematic diagram showing the relationships between the three rock types and the processes within the rock cycle.
Igneous rocks form from the cooling of molten material in the subsurface (intrusive igneous rocks) or at the surface (extrusive igneous rocks). Igneous, metamorphic, and sedimentary rocks exposed at the surface through uplift and erosion are
oken down into sediment which is then transported from areas of high topographic relief to areas of low topographic relief where they are deposited and then lithified. Through sedimentary burial, tectonic processes, or magmatic activity rocks at the surface fall deeper into the earth, becoming exposed to the higher temperatures and pressures necessary to initiate metamorphosis. With too much heat, the rocks melt completely and join magma bodies in the subsurface. The cycle repeats as rocks become exposed, eroded, deposited, metamorphosed, and buried (see Figure 4).
Figure 4. A simplified conceptual diagram of the rock cycle.
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The Three Rock Types in El Paso, TX
El Paso is a wonderful place to observe all kinds of geologic history and processes. With the exception of the Castner Ma
le, most of it is incredibly easy to access and observe (sees Figure 5 through 9). Drive through the transmountain road to see if you can catch a glimpse of the thunde
ird igneous intrusion (Figure 6) where magma squeezed between older limestones before cooling and crystallizing. If you are interested in clastic sedimentary rocks, explore the rocks outcropping around Christo Rey! (Figure 8). Dinosaur tracks are well preserved in some of these layers and can be spotted from just off of the road. UTEP geologists sometimes lead public field trips to these locations as well! If you are interested in biochemical sedimentary rocks take a walk along scenic drive when it is closed to cars and open to the public (Figure 9). Look at the rocks along the walkways and try to find evidence of ancient marine life preserved as fossils in the outcrop.
Figure 5. Panoramic photo and geologic model of the Franklin Mountains near the trans-mountain road in El Paso, TX.
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Figure 6. A view of the thunde
ird intrusion at El Paso, TX. Intrusive igneous rocks seen near the transmountain road.
Figure 7. A photo of the Metamorphhic Castner Ma
le near Fort Bliss, El Paso, TX.
Figure 8. A photo of the dinosaur tracks preserved in clastic, sedimentary rocks (sandstone) near Christo Rey.
Figure 9. A photo of ca
onate outcropping along scenic drive. Biochemical sedimentary limestones.
Part III. Geological Methods to Study Earth’s Interio
Method 1: Studying uplifted rocks from beneath the earth's surface
Through various mountain building processes related to plate tectonics, parts of the earth that were once buried deeply may become exposed at the surface, letting us explore the composition and textures of the rock layers beneath our feet. One example is from an Ophiolite outcrop. An Ophiolite is a slice of Earth's oceanic crust and co
esponding mantle (see more on Figure 10) that has been exposed on a continent above sea level. By studying it geologically, geophysically, and geochemically scientists can gain insight into how deep parts of the earth form, what they are made of, and how we can use geophysical tools to better investigate them. The example in Figure 10 is an example of an Ophiolite outcrop exposed in the Sultanate of Oman, located on the Arabian Peninsula. Shown in the photos and geologic model next to it, scientists were able to identify the igneous rocks and their respective fa
ics that make up a typical piece of oceanic crust. They were also able to identify Wehrlite and Dunite layers that co
espond to the Moho transition zone, which is a geophysically resolvable boundary that marks the transition from earth's crust to its deeper mantle.
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Figure 10. Ophiolite outcrop exposed in the Sultanate of Oman, located on the
Arabian Peninsula. The geologic model is shown next to it on the left.
Method 2: Studying seismic waves travelling through the Earth
Earthquakes are geologic events where the surface of the earth shakes due to a sudden
eak deep within the earth's subsurface. These
eaks send waves, known as seismic waves, throughout the entire earth. Seismologists, scientists that study these waves, are able to track them and observe how they interact differently with different layers of the earth. There are three types of waves that they focus on: P waves (compressional waves), S waves (Shear waves) and L waves (surface waves). P waves travel faster than the other waves and can pass through liquids, gases or solids. In contrast, S waves are slower and cannot pass through liquids. This helps us differentiate between solid and liquid layers in the subsurface. In recording the travel times between waves at a known earthquake and research stations on the surface of the earth, scientists can map the subsurface and determine where earthquakes originate from (see Figure 11).
Figure 11. A schematic showing how earthquakes