Geology 101
Midterm Exam Study Guide
The Midterm Exam will cover Introduction to Geology, The Rock Cycle, Minerals, Bowens
Reaction, Volcanoes and Igneous Activity, Weathering and Sedimentary Environments and
Metamor
...
Geology 101
Midterm Exam Study Guide
The Midterm Exam will cover Introduction to Geology, The Rock Cycle, Minerals, Bowens
Reaction, Volcanoes and Igneous Activity, Weathering and Sedimentary Environments and
Metamorphism. Essay questions will be pulled from the following questions. Multiple choice
questions will also cover lecture and lab materials covered in class.
Introductions and Minerals
• Define “hypothesis” and describe how a hypothesis becomes a scientific theory
A hypothesis is a tentative explanation that can be tested by further investigation
If a refined hypothesis survives all attacks on it and is the best existing explanation for a
particular phenomenon, it is then elevated to the status of a theory.
• Describe and atom and its basic components. Key Terms: electron, neutron, proton,
nucleus, orbital, charge.
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of
the atom contains the protons (positively charged) and the neutrons (no charge). The outermost
regions of the atom are called electron shells and contain the electrons (negatively charged).
• Describe the basic framework of a silicate mineral. Key Terms: silica tetrahedron,
sharing, cations, crystalline.
The simplest silicate structure, that of the mineral olivine, is composed of
isolated tetrahedra bonded to iron and/or magnesium ions.
• What physical characteristics can you use to identify minerals (i.e. mineral
properties)?
hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity.
Igneous Activity
• Magma is generated in three (3) ways. List and give a description of each method. Be
sure to note HOW the parameter has to change in order to induce melting.
Magma and lava contain three components: melt, solids, and volatiles. The melt is made of
ions from minerals that have liquefied.
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• Look at the diagram of Bowen’s Reaction Series. Explain what the series tells you about
order of crystallization of minerals in magma, and what minerals you might expect to
find in rocks of mafic, intermediate, and felsic compositions. Finally, (1) comment on the
relative stability of these minerals on the Earth’s surface (which ones weather easily or
are fairly resistant to weathering).
Mafic: A mafic (portmanteau of "magnesium" and "ferric") mineral or rock is a silicate
mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color,
and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite.
Common mafic rocks include basalt, diabase and gabbro.
Intermediate: Intermediate rocks are roughly even mixtures of felsic minerals (mainly
plagioclase) and mafic minerals (mainly hornblende, pyroxene, and/or biotite). There is little
or no quartz. Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and
less than 15% mafic minerals (biotite, hornblende).
Felsic: In geology, felsic is an adjective describing igneous rocks that are relatively rich in
elements that form feldspar and quartz. Common felsic minerals include quartz, muscovite mica,
and the orthoclase feldspars.
Rocks and the Rock Cycle
• Describe two (2) reasons sedimentary rocks are important to science (as covered in
lecture).
coal, fossil fuels, drinking water and ores. Used for buildings in construction. Asphalt
• Weathering, physical vs. chemical weathering, examples?
Physical, or mechanical, weathering happens when rock is broken through the force of another
substance on the rock such as ice, running water, wind, rapid heating/cooling, or plant growth.
Chemical weathering occurs when reactions between rock and another substance dissolve the
rock, causing parts of it to fall away.
• What is erosion?
Erosion is the geological process in which earthen materials are worn away and transported by
natural forces such as wind or water
• Transportation, how is sediment transported
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