Geology Curriculum & Labs

1. DIFFERENTIATION OF EARTH’S LAYERS

How did the Earth differentiate into its various layers?

2. ACTIVE EARTH: FROM
CONTINENTAL DRIFT TO PLATE TECTONICS

What evidence do we have to support the plate tectonic theory?

3. MINERALOGY: THE BUILDING BLOCKS OF OUR ROCKS

What is a mineral and what properties distinguish one mineral from another?

4. ROCKS VS. MINERALS

What distinguishes a rock from a mineral?

5. OHIO’S SEDIMENTARY BASINS

What processes are responsible for the formation of the bedrock found in Ohio’s sedimentary basin?

6. EARTH’S ENERGY SOURCES

What natural resources are used to create energy in Ohio & how are those processes related to the carbon cycle?

1. DIFFERENTIATION OF EARTH’S LAYERS

How did the Earth differentiate into its various layers?

BACKGROUND

The Earth formed some 4.6 billion years ago from a swirling mass of nebular material. This material coalesced and accreted into a solid mass. The temperature of early Earth steadily increased due to the high-velocity impact of nebular debris and the decay of radioactive material. This early period of heating resulted in the chemical and physical differentiation of Earth establishing the Earth’s concentric layers. 

Through the use of seismic (sound wave) data, scientists are able to accurately map out Earth’s internal structure. There are thousands of earthquakes that occur every day around the world. Earthquakes are shaking motions and vibrations of the Earth caused by large releases of energy that accompany volcanic eruptions, explosions, and the movement of the plates along its boundaries. There are currently over 3,000 active seismic recording stations located around the world. Each of these stations utilizes a device called a seismograph that generates a written record as a seismogram of the seismic event.

Most earthquakes are associated with energy being released along fault boundaries. All faults have some type of stress associated with them, compression, tension, and/or shear stress. This stress being exerted on a body of rock is stored as elastic energy. A body of rock can only withstand a certain amount of stress without permanent change in size or shape; this is that body of rocks elastic limit. When the stress on the body of rock exceeds its elastic limit the body of rock will rupture, brittle fracture occurs, and elastic energy stored in the body of rock is suddenly released as seismic energy; the seismic energy released causes the shaking of the ground. 

Seismic energy is suddenly, without warning, released along a fault boundary. This energy is carried outward in all directions by various seismic waves, some of which can reach the opposite side of the Earth in about twenty minutes. Seismic waves radiate outward from the initial point of rupture along the fault line at the hypocenter (focus). Seismic waves generated from the focus, called body waves, consist of both Primary waves (P waves) and Secondary waves (S waves). Located directly above the focus at the surface of the Earth is the Epicenter. Seismic waves, called surface waves, radiate outward in all directions at the surface from the epicenter. These surface waves are identified as Rayleigh and Love waves 

As seismic waves pass through the Earth they encounter boundaries of different density within the interior of the Earth. These boundaries of different densities will cause the seismic waves to reflect or refract (bend) as the seismic waves pass through a boundary of different density. This reflection and refraction of the seismic wave is caused by a change in speed of the seismic waves as they encounter materials with different density. Based on the arrival times of the P and S waves around the Earth scientists can generate an internal image of the Earth’s structure.

The use of seismic technologies also dominates the field for the exploration of deep underground reservoirs of hydrocarbons. Just as geologist use seismic data from earthquakes to depict an image of the interior of the Earth, geophysicists use reflection seismology to explore specific regions for hydrocarbons. Geophysicists deploy some type of acceptable energy at the surface to generate seismic waves that radiate out from the source station as a three-dimensional wave. As these waves propagate down through the Earths layers a portion of the wave is reflected back to the Earth’s surface and is recorded by a device called a geophone. The geophones are distributed in specific geometries at the surface to produce a very detailed image of the geology of the area of interest.

ACTIVITIES

1.1 Differentiating Earth’s Layers

How did the Earth differentiate into various layers?

2. ACTIVE EARTH: FROM CONTINENTAL DRIFT TO PLATE TECTONICS

What evidence do we have to support the plate tectonic theory?

BACKGROUND

In 1915, German meteorologist Alfred Wegener proposed his hypothesis of Continental Drift. Wegener proposed that the continents were not of fixed position, rather they moved very slowly over time. Wegener suggested that all the continents were once joined together as a supercontinent, Pangea, that existed during the late Paleozoic and Early Mesozoic and had since broke into smaller plates that had drifted apart.  Wegener’s hypothesis of Continental Drift was widely rejected by the scientific community, even with the evidence of the supercontinent Pangea, because it lacked a viable driving mechanism to explain the proposed motion of the plates.

It was another 50 years before Wegener’s theory was resurrected by research being conducted during World War II. Exploration of the ocean floor provided evidence in support of Wegener’s hypothesis including an extremely long mid ocean-ridge system, and that oceanic crust was relatively young relative to the continents. Considerable research was conducted to find a means of detecting large steel objects beneath the ocean surface (submarines). As a result, sensitive equipment was constructed that could detect very small changes in the Earth’s magnetic field – and could be carried in aircraft and used to survey large areas from the air. Surveys of the oceans, and in particular, areas on either side of the mid-ocean ridges, showed patterns of magnetic anomalies that were repeated (mirrored) on either side of the spreading ridge.

The Modern Plate Tectonic Theory states that the lithosphere is divided into rigid plates that diverge (pull apart), converge (come together), or slide past each other as they move over the asthenosphere. The motion of the lithospheric plates is a result of convection within the Earth’s mantle, the outward push of the diverging plates (ridge push) along the mid-ocean ridge system, and the pull of the subducting oceanic plates (slab pull) back into the mantle along convergent plate boundaries. The heat that drives the convection within the mantle is in part left over primordial heat from the formation of early Earth and the radioactive decay of elements such as uranium and thorium and their decay products from deep in the interior of the Earth. 

The movements of the plates and the interactions of plates along their boundaries cause volcanic eruptions, earthquakes, the formation of mountain ranges and new ocean basins, and is responsible for the recycling of rock material and production of many of Earth’s naturally occurring economic resources. Oil, natural gas, and coal are the byproducts of the accumulation of organic materials, deep burial, and decomposition within a sedimentary basin that flanks mountain ranges formed by plate tectonic processes. Oil, natural gas, and coal found in Ohio are by in part a result of Ohio being a sedimentary basin for the Appalachian Mountains formed millions of years ago. The theory of Plate tectonics is considered a unifying explanation for many geologic features and events and provides a framework for interpreting the composition, structure, and internal processes of Earth on a global scale.

3. MINERALOGY: THE BUILDING BLOCKS OF OUR ROCKS

What is a mineral and what properties distinguish one mineral from another?

BACKGROUND

Minerals are the building blocks of rocks; rocks are composed of minerals. Minerals are naturally occurring, inorganic, crystalline structure with a specific chemical composition. Minerals are composed of atoms of one or more elements that combine in such a way to give that mineral its specific chemical structure.

The chemical bonding and composition unique to each mineral will result in specific properties that are individual to each mineral and its chemical structure. These properties are therefore useful when identifying minerals, and include: hardness, color, clarity, streak, crystal form (habit), cleavage, fracture, tenacity, and density. Other useful properties of minerals sometimes include: smell, taste, reaction to hydrochloric acid, magnetism, and double refraction of light.

Minerals can form under a variety of conditions, such as: during the cooling of molten materials (from lavas, igneous rocks), during the evaporation of liquids (salt, gypsum, the cooling of liquids (saturated solution). At high temperature and pressures new crystals may also grow in solid materials (metamorphism).

There are thousands of minerals that have been identified, but only a few are common to the Earth’s crust and these are referred to as rock-forming minerals. Silicate minerals dominate the Earth’s crust and form when the two most common elements (silicon and oxygen) in the Earth’s crust combine. The clay minerals, kaolinite, smectite, illite, and chlorite are ever-present in the rocks being targeted for the exploration of hydrocarbons. Studying clay mineralogy of specific source rocks is important since clay minerals and organic matter are responsible for the formation of hydrocarbon generation and typically coexist in the same sedimentary rocks. It is the mineralogy that drives geologists to study potential source rocks (typically organic-rich shales) and helps make the determination of the organic materials in the source rocks that can produce hydrocarbons.

The formation of minerals in Ohio over the course of Earth’s geologic past has produced six nonfuel minerals (also called industrial minerals) and coal. Primarily used as construction minerals these industrial minerals include: limestone and dolomite, sand and gravel, sandstone and conglomerate, clay, shale, and salt. Of Ohio’s 88 counties, 87 of those counties have had at least one of these mineral commodities mined. According to the Ohio Department of Natural Resources, of the 564 industrial-mineral-mining operations known to be operating in 2014, 335 operations were reported as active. The economic value of Ohio’s coal and industrial minerals in 2014 totaled nearly $2 billion.

4. ROCKS VS. MINERALS

What distinguishes a rock from a mineral?

BACKGROUND

Mineralogy is the study of geochemistry. Petrology is the study of rocks. Rocks are naturally occurring aggregates of minerals. Unlike minerals, rocks do not have definite chemical structure and composition. Rocks are classified by their composition, textures, and the processes that account for their formation. These factors differentiate rocks into three different categories: igneous, sedimentary, and metamorphic.

Igneous (ignis = fire) rock forms as molten rock cools and solidifies into a crystalline solid. The cooling of magma and lava results in the crystallization of minerals and the formation of an igneous rock. Magma that cools and crystallizes below the surface forms intrusive (plutonic) rocks. At the surface lava solidifies and volcanic debris (pyroclastic material) forms extrusive (volcanic) rocks. Where these rocks cool and solidify results in textures that are specific to their formation. 

Sedimentary rocks are typically layered rocks that are derived from the weathering and erosion processes that form sediments. Approximately 75% of exposed land surface is covered by sediments and sedimentary rocks, as well as the majority of the ocean floor. These sediments will eventually be deposited and become lithified (compacted and cemented) to form a new sedimentary rock. 

Sedimentary rocks can be classified into two different groups: detrital and chemical/organic sedimentary rocks. Detrital (clastic) sedimentary rocks have a texture that consists of small rock fragments and particles that are compacted and cemented together. Detrital sedimentary rocks are subdivided primarily by grain size and roundness of the clast particles. Chemical/organic sedimentary rocks are subdivided into groups based on the mineral composition of the rock. 

About half of the world’s oil and gas, much of its groundwater, and extensive deposits of metallic ores are held in carbonates. Carbonate sediments commonly form in shallow warm oceans either by either direct precipitation out of seawater or from the biological extraction of calcium carbonates from seawater in the form of skeletal material. Carbonate rocks are composed of Calcium carbonate (CO3). When carbonates break down they produce carbon dioxide and water (CO2). This reaction commonly occurs when acid is placed on a carbonate rock like limestone. The resulting reaction causes the carbonate to fizz, distinguishing carbonates from detrital sedimentary rocks. The Earth’s crust stores the largest amount of carbon, where it is a part of a variety of different rock types, with limestone being the largest depository.

Metamorphism (to change form) is a process in which a parent rock undergoes changes in the mineralogy, texture, and sometimes the parent rocks chemical composition. Every metamorphic rock forms from a preexisting rock, be it a metamorphic, igneous, or sedimentary rock, called the parent rock. Metamorphism of a parent rock results in metamorphic textures that describe the size, shape and arrangement of mineral crystals of a metamorphosed rock. Metamorphism of rocks results from subjecting the parent rock to heat, confining pressure, directional (differential) stress, and chemically active fluids. Each of these agents of metamorphism may contribute to the degree of metamorphism, but each agent will vary from one environment to another. Heat is the primary agent responsible for metamorphism; heat provides the necessary energy to chemically alter the parent rock that results in the recrystallization of existing minerals. 

Due to the driving forces of the water cycle and plate tectonics, rocks do not remain the same throughout geologic time. Rocks are forced to undergo change as their environments change over time, this process of change is reflected in the rock cycle.

Minerals are very beautiful but also are important to society. It is the mineralogy of the rocks that drives geologists to study particular potential source rocks (typically organic-rich shales) and make the determination that the organic material in the source rock can produce hydrocarbons. Shale characteristics important to the oil and gas industry include; where and how much is present, how much organic matter it contains, the type of organic matter (gas- vs. oil-rich shale), clay and other minerals it contains, how deeply it was buried and “cooked”, its brittleness vs. ductility (break or bend), and how fractured it is (natural fractures). All of these characteristics vary in a shale formation across a region, and it’s these characteristics that are unique to Marcellus and Utica shales that have driven these oil plays in Ohio.

ACTIVITIES

4.1 Is It a Rock or a Mineral

How are rocks and minerals related?

4.2 Rock Classification by Design

How are rocks classified?

4.3 Making Igneous Rock Inferences

How do geologists identify igneous rocks?

4.4 Making Sedimentary Rock Inferences

How do geologists identify sedimentary rocks?

4.5 Making Metamorphic Rock Inferences

How do geologists identify metamorphic rocks?

5. OHIO’S SEDIMENTARY BASINS

What processes are responsible for the formation of the bedrock found in Ohio’s sedimentary basin?

BACKGROUND

The weathering of existing rocks is responsible for producing the sediments that will form the sedimentary rocks we find today. The mechanical (physical) weathering processes responsible for deriving these sediments include frost wedging, crystallization of salt, pressure release, the action of organisms (tree roots), and thermal expansion. These processes work to break rocks into smaller particles (sediments) that have the same chemical compositions as their parent rock. Rocks may also be weathered by chemical processes as minerals in a rock react with its new environment. Water and oxygen play a significant role in the chemical weathering of rocks by dissolution, oxidation, hydrolysis, and spheroidal weathering. The rate at which rocks begin to break down is a function of the rock types (mineralogy) resistance to weathering and the environment (temperature/rainfall). Sediments are carried off and deposited in a new location by running water, wind, glaciers, and gravity.

By interpreting today’s sediment depositional environments geologists are able to infer what past environments may have looked like, this geological principle is referred to as uniformitarianism.

Understanding the depositional environments from which the sedimentary rocks have formed, geologists are able to infer the history of a sedimentary rock including; sediments methods of transport, origins of its particles, and the environment of deposition. Most importantly to the hydrocarbon industry are the environments associated with the movement of carbon from the atmosphere, biosphere, hydrosphere and ultimately to the geosphere.

Most of Ohio’s bedrock reflects depositional environments associated with marine type environments. This is the result of periods of marine transgressions and regressions over the state of Ohio. Marine Transgressions occur when sea level rises relative to the land. This is reflected in the rock record as deeper sea sediments (shales and limestones) being deposited on top of continentally derived beach sediments (sandstones). Marine regressions occur when sea level falls relative to the land. Marine regressions are reflected in the rock record as continentally derived beach sediments (sandstones) being deposited on top of deeper sea sediments (shales and limestones). It was these periods of sea level change over the course of millions of years ago in Ohio that is responsible for setting the stage for the oil and gas production we see today. During the Devonian period when most of Ohio was under water, sediments were shed from the Acadian mountains to the East of Ohio and deposited in the deep ocean over Ohio. It was the fine grained, rich organic sediments that were deposited during the Devonian that are responsible for the gray and black Devonian shales (Marcellus shales) present in Ohio today. 

The major contributors for the production of hydrocarbons (petroleum, natural gas, and coal) in Ohio are directly associated with the organic rich environments in which those source rocks were deposited. A source rock is any rock type that will generate hydrocarbons and is typically found in gray or black shales, particularly the Utica and Marcellus shales plays in Ohio. Some limestones, coal and other rock types can on occasion generate hydrocarbons as well. The organic material responsible for the production of hydrocarbons in the source rocks includes marine algae, marine planktonic organism and bacteria, and terrestrial plants (leaves and stems). This organic material is incorporated into the source rock at the time of deposition. The greater the total organic carbon in a source rock the more hydrocarbons it is capable of producing. Organic rich rocks are associated with a variety of depositional environments including deep water marine (ocean), lakes, deltas, and swamps. Many environments have organic rich sediments but not all of those deposits will produce hydrocarbons. This is partly due to most of the organic material being consumed by local organisms prior to burial or the organic material being oxidized as it decays. For an environment to have the potential to produce hydrocarbons, burial of the organic material must happen rapidly (geologically speaking) to preserve the organic material, be deprived of oxygen to decrease the rate of oxidation, and have very few organisms present to reduce consumption of the organic material. As sediments are deposited rapidly on top of the organic rich rocks temperature and pressure increases with depth. This increase in temperature and pressure heats the organic material and generates the hydrocarbons in the source rocks.

It is the result of living organisms from millions of years ago that we have the many hydrocarbon resources available to us today.  The coal we use to generate electricity and the crude oil we refine are the products of these organisms being deposited, buried, heated, changed into hydrocarbons, trapped and stored in the Earth’s crust.

6. EARTH’S ENERGY SOURCES

What natural resources are used to create energy in Ohio and how are those processes related to the carbon cycle?

BACKGROUND

Most of Earth’s energy resources are derived from previous and current natural processes in which solar energy from the Sun is either stored or directly used. Energy resources derived from our Sun includes direct solar power, coal, oil, natural gas, biomass, wind, and hydropower. Earth’s energy resources can be defined as renewable or nonrenewable. Nonrenewable energy resources are those stored over millions of years in geologic time and once used cannot be readily replaced by natural means relative to their rate of consumption. Nonrenewable energy resources stored in different forms of carbon created from plants and animals include peat, coal, oil, and natural gas. Renewable energy resources can be replenished or replaced in a time that is relatively equal to or less than the time it takes to consume the supply. Renewable energy resources include things such as biomass, wind, solar, hydroelectric, and geothermal energy.

According to the U.S. Energy Information Administration Ohio is among the top 10 states in total energy consumption in the Nation. Ohio’s energy needs are derived from both renewable and nonrenewable energy resources. Nonrenewable energy resources such as natural gas, coal, and oil supply the majority of Ohioans’ daily energy needs. Renewable energy resources such as wind, biomass, solar, and hydroelectric power, currently supply about 7% of Ohio’s energy needs, with nuclear power fulfilling the remaining.

Nonrenewable Energy Resources

Coal is the nonrenewable energy resource primarily used for fuel for electricity generation in Ohio. Eight of Ohio’s 10 largest power plants by capacity are coal-fired. In recent years, coal’s share of generation and the number of coal-fired power plants in the state has decreased. In 2015, 15% of the state’s coal-fired generation capacity was retired. However, coal still fuels more than half of the state’s electricity generation. Coal has a higher concentration of carbon emissions as compared natural gas when combusted for electric generation.

Natural gas is the fastest growing nonrenewable energy resource in Ohio and is used to fuel electric generating facilities, fuel natural gas powered vehicles, provide heating, and is used in industrial manufacturing applications across the state. Ohio’s total current combined coal, natural gas, and nuclear electric generating capacity is 25,000 Megawatts, with coal accounting for 59%, natural gas contributing, 23%, and nuclear 14%. Ohio’s natural gas reserves and production have increased substantially in recent years. In 2015, natural gas production in Ohio was more than 12 times greater than in 2011, rising from less than1% of the nation’s total to 3% of the total. Much of the additional natural gas production is from the extraction of gas from the Utica Shale using modern horizontal drilling and completion technology that allow for the safe and efficient production of gas from a single well over large areas. One horizontal gas well can now produce what previously took several wells. 

Crude oil in Ohio is primarily refined into products such as engine lubricants, plastics, and gasoline. Crude oil production and proved reserves in Ohio are modest, although greater than any other Appalachian Basin state except Alabama. Ohio’s crude oil production was less than 10 million barrels annually for most of the past 25 years, but increased drilling using advanced technologies resulted in a 30-year high of more than 14 million barrels in 2014. Production almost doubled to more than 26 million barrels in 2015, but it is still less than 1% of the nation’s total. Ohio’s proved crude oil reserves reached a 28-year high of 78 million barrels in 2014. Drilling in the Utica Shale formation accounts for much of the increase, and it has significantly added to Ohio’s production and reserve base. Ohio is consistently among the top 10 oil-refining states in the nation.  

Renewable Energy Resources

Ohio has a diverse biomass energy resource that has been utilized since Native Americans and Settlers first utilized our abundant forests. There are 20 separate small-scale biomass-fueled power plants in Ohio. Biomass from wood and wood waste, municipal solid waste, landfill gas, and biodigester-derived gas is utilized for Ohio’s net electricity generation and home and business heating needs. 

Biomass in the form of corn and soybeans in Ohio has also been increasingly used over the last two decades to create ethanol and biodiesel to power Ohioans’ transportation needs. Ohio is the seventh-largest ethanol-producing state in the nation. All but one of the state’s nine ethanol plants use corn as a feedstock. The remaining plant uses waste industrial alcohol. Ohio’s ethanol plants produce almost 530 million gallons of ethanol per year, and the state’s share of U.S. ethanol consumption is almost equal to its share of the nation’s production capacity. Ohio has two biodiesel plants that process soy oil into biofuels. The combined capacity of the two plants is about 65 million gallons per year. 

Wind turbine facilities provide one of the largest shares of energy production from renewable energy resources in Ohio, and net generation from wind in the state has increased dramatically since Ohio’s first utility-scale wind farm was constructed in Bowling Green in 2004. Ohio has approximately 400 Megawatts of installed utility-scale wind-powered installations. 

Electricity derived from solar panel projects in Ohio is currently 118 Mega Watts. This ranks Ohio as the 23rd in the Nation for installed solar capacity. The solar power derived from these projects can provide enough energy for approximately 14,000 Ohio homes. 

Hydroelectric facilities provide 130 Megawatts of electricity capacity statewide. Solar, wind, and hydroelectric power have some of the lowest carbon emissions as compared to other energy resources in Ohio. 

Carbon Cycle

Carbon is a critical chemical element in the utilization of our energy resources in Ohio and the world. The Carbon Cycle is a model that relates the amounts of carbon in the atmosphere, oceans, and crust to the processes that change those amounts. The processes involved in the carbon cycle have been dynamic over the geologic history of the earth and in modern history, and are the focus of many scientists in Ohio and throughout the world. The carbon cycle involves the movement of carbon among the Earth’s oceans, atmosphere, ecosystems, and geosphere. Carbon is present in the Earth’s atmosphere as both carbon dioxide (CO2) and in smaller quantities of methane gas (CH4). Carbon is a fundamental building block of life and an important component of many other chemical processes. Processes that predominantly produce CO2 are defined as sources, and processes that take in or store CO2 are sinks (reservoirs). The utilization of Ohio’s nonrenewable and renewable energy resources all have an impact on the carbon cycle.

Through the process of absorption and photosynthesis carbon is absorbed by plants and animals, with plants releasing oxygen into the environment and animals consuming oxygen. Some of the carbon remains in the plants and animals. When the plants die, decay or are burned, CO2 is returned to the atmosphere. In some sedimentary basins the accumulation and burial of dead plant material that has not been decayed back into CO2 is deposited as sediments. When a large amount of plant material (biomass) is buried with sediment over long periods of geologic time some of these carbon rich deposits become layers of coal or are converted into hydrocarbons such as natural gas. When many sea dwelling animals die their degradable remains are entombed into marine sediments and are then converted into oil by heat and pressure over geologic time during sediment accumulation. When sea creatures with hard parts such as calcareous shells (seashells) die these remains can also accumulate as sediments and form tremendous limestone deposits. The Earth’s crust stores the largest amount of carbon in a variety of different rock types, with limestone’s and shales being the largest carbon sinks in the earth’s crust. The earth’s ecosystems, oceans, and atmosphere are the most dynamic portions of the carbon cycle where source and sink carbon balances change over geologic time, decades, and annually or even daily. Annual growth of northern hemisphere forest such as in Ohio which take in CO2 during the summer at higher rates than in the winter are an example of annual changes in carbon intake into the ecosystem sink. 

Sources

  • Respiration: CO2 released by plants and animals

  • Decay: decomposers break down organic materials releasing CO2

  • Combustion: burning any substance such as wood or coal that contains Carbon releases CO2 

Sinks (reservoirs)

  • Atmosphere: mostly in the form of CO2

  • Plants: Photosynthesis

  • Soil and Organic Matter: Carbon stored in the dead plant material

  • Coal, oil, gas: Hydrocarbons stored in fossil fuels

  • Ocean: Ocean water absorbs CO2 from atmosphere; microscopic plants (phytoplankton) take up CO2, shelled organisms take up CO2 to form shells

  • Sediments/Sedimentary Rock: sediments containing Calcium Carbonates from shells and carbon from decaying phytoplankton can turn into rock, some trapped carbon can turn into oil and gas.

ACTIVITIES

6.1 Tracking the Carbon

Is it a carbon source or a sink (reservoir)?

6.2 Carbon from Rock

Is carbon stored in rocks?