1. What Does a Geologist Do?
NSF North Mississippi GK-8

2. What Does a Geologist Do?
Studies the origin, history, and structure of the earth
NSF North Mississippi GK-8

3. NSF North Mississippi GK-8
The Layers of the Earth
The surface of the earth usually looks the same to us from year to year; yet it is always changing, and has been changing since the world was first formed. The earth is built out of a series of layers. The outer layer or surface of the earth is called the crust. The earth's crust consists of the continental and the oceanic crust. The continental crust is around 20 miles deep. The buoyancy of the granitic rocks lets the crust float on the earth's mantle. The oceanic crust is the ground below our oceans; it is thinner then the continental crust and has an average of miles in depth.
Several tectonic plates make up the earth's crust that are in a constant state of process. These plates move around or drift very slowly, and the earth's surface gradually shifts position over millions of years. As they move, they may slide by each other, move apart, dive beneath one another, or collide head-on. The mantle is a thick layer of rock below the earth's crust; it is about 1,800 miles deep. The rock in the mantle is made of silicon, oxygen, aluminum, iron, and magnesium. It is mostly a solid silicate rock.
The outer core begins about 1,800 miles below the earth's surface. The material of the outer core is believed to be solid; it consists of mainly melted iron, and may contain a small amount of some other elements, most likely oxygen or sulphur. It is a liquid molten core of nickel and iron.
The innermost part of the earth is called the core. It makes up the center of the earth. It is about 3,400 kilometers below the earth's surface. The core consists mostly of iron, with lesser amounts of nickel and silicon which is combined with a small amount of other elements, most likely sulphur or oxygen.
The layers of the Earth: The earth is divided into three main layers, the crust, mantle, and core. The crust consists of soil, fragmented rock, and rigid bedrock. The mantle consists of mostly rigid rock, but some rocks in the mantle flow like toothpaste. The core is divided into the outer core and the molten inner core. Geologists are not yet able to drill even to the base of the crust.
NSF North Mississippi GK-8

4. NSF North Mississippi GK-8
Crust: Soil and Rock
Crust: Since we live on the crust, it is important for geologists to extensively study the crust. The crust is composed of soil and rock. Rocks are made of minerals, and soil is made of broken pieces of rocks and minerals.
NSF North Mississippi GK-8

5. NSF North Mississippi GK-8
Minerals
Minerals: Minerals are naturally occurring, inorganic, substances with a characteristic chemical composition, distinctive physical properties, and crystalline structure. Rocks are composed of one or more type of mineral. Show the mineral examples and place them aside. Students will be allowed to come up and look at the end of the presentation.
earthhttp://
NSF North Mississippi GK-8

6. NSF North Mississippi GK-8
Rocks
Rocks are made of minerals
There are 3 types of rocks:
Igneous
Metamorphic
Sedimentary
All 3 form in different ways
Igneous rocks form when magma or lava cools to a solid state.
Metamorphic rocks are rocks changed from one form to another by intense heat, intense pressure, or the action of hot fluids.
Sedimentary rocks are formed when fragments of plants, animals, or other rocks are compressed together or hardened.
NSF North Mississippi GK-8

7. NSF North Mississippi GK-8
Igneous
Rocks
Igneous Rocks: Igneous rocks are formed when magma or lava cool to a solid state as either glass or masses of different minerals grown together. Magma is molten rock below the surface of the earth and lava is magma that has risen to the surface of the earth. Show the examples of igneous rocks. Show that pumice will float by placing it in a cup of water. Explain that this is because so many air bubbles were trapped when the lava or magma was cooling. Scoria has many air bubbles as well. Explain that obsidian cooled so fast that it turned to volcanic glass.
NSF North Mississippi GK-8

8. NSF North Mississippi GK-8
Sedimentary
Rocks
Fossils
Sedimentary Rocks: Sedimentary rocks are formed when fragments of plants, animals, or other rocks are compressed together or otherwise hardened, or when masses of minerals precipitate from water. Sediments from rocks and minerals are deposited by wind and water and then harden into rock. Many fossils are preserved in sedimentary rocks. Layers and layers of sediment pile on top of a plant or dead animal, and when the sediment layers eventually turn to stone, the imprint of the animal or plant is preserved. Explain that sandstone is composed of sand grains and mudstone is composed of clay and silt grains that were cemented together. Shale is a specific type of mudstone, made mostly of clay. Coquina is composed of shells and shell fragments that were cemented together. It is a type of limestone called skeletal limestone.
NSF North Mississippi GK-8

9. NSF North Mississippi GK-8
Metamorphic Rocks
Metamorphic rocks were once sedimentary, igneous, or another metamorphic rock. These rocks are physically deformed and chemically changed due to different temperatures and pressures. The elements in the minerals can actually "move" to form new minerals. The rock does not melt, or else it would be considered an igneous rock. A rock looks different after it has been metamorphosed. The rocks texture and overall appearance changes also. It now has a squished look!
Metamorphic Rocks: Metamorphic rocks are rocks changed from one form to another by intense heat, intense pressure, or the action of hot fluids. Metamorphic rocks could have been sedimentary rocks, igneous rocks, or even different metamorphic rocks before undergoing metamorphism to become new metamorphic rocks. Explain that when sandstone is metamorphosed it turns to quartzite, when shale is metamorphosed it turns to slate, and when limestone is metamorphosed it turns to marble.
NSF North Mississippi GK-8

10. Soil: Gravel, Sand, Silt, and Clay
NSF North Mississippi GK-8

11. So, what do geologists do?
Mining
Subsurface investigation
Roads
Foundations
Groundwater
Satellite imagery
Make geologic maps
So, what do geologists do? Geologists do all kinds of different jobs. They can work in mines, they can investigate what it like underground, they can help build roads, they can help build foundations for homes and buildings, they can find and monitor safe drinking water, they can work with satellite imagery, and they can make geologic maps.
NSF North Mississippi GK-8

12. NSF North Mississippi GK-8
Mining
Mining: Geologists mine the earth for valuable rocks and minerals. That means they investigate an area, and if they see something valuable that could be used to make things, they dig it up. Minerals are used to make almost everything that we use daily. Take a pencil, for example. The eraser is hardened with the mineral sulfer. The metal part that holds the eraser is made from the minerals sphalerite and chalcopyrite. The lead is made from a mixture of the minerals graphite and kaolinite. (Show pencil while talking about this).
NSF North Mississippi GK-8

13. Subsurface Investigation
Subsurface Investigation: Subsurface investigation means to figure out what is below the ground. Subsurface investigations are important for determining if drinkable groundwater is available, if the soil is suitable to build on, or to determine if there is anything worth mining. Geologists investigate what is below the surface by drilling straight down and pulling out a cylinder of soil and rock called a core. They can look at this core sample and know exactly what’s below! The people in the picture are taking a core sample by twisting a sharp tool into the ground. There are also large drilling machines that are commonly used. Show the example of the core sample.
NSF North Mississippi GK-8

14. NSF North Mississippi GK-8
Roads
Roads: A team of professionals build our roads. Geologists are always a part of that team to make sure that the ground is safe. Take a look at this picture. This is what can happen to the roads if they are not built in the proper location!
NSF North Mississippi GK-8

15. NSF North Mississippi GK-8
Foundations
Foundations: A team of professionals also build the foundations for houses and buildings. What do you notice about this building? It’s leaning! That’s because the building settled into the soil. Think about when you walk on mud. Your feet sink into the ground. That’s the same thing that happened to this building- it sunk a little bit. Geologists are responsible for testing the soil and getting it ready for a building to be built.
NSF North Mississippi GK-8

16. NSF North Mississippi GK-8
Groundwater
Soil
Water and Soil
Rock
Groundwater: When it rains, the water runs over the land and into streams, or forms puddles and eventually evaporates or sinks into the ground. The water that sinks into the ground gathers in underground reservoirs called aquifers. We get most of our drinking water from aquifers. Geologists locate aquifers and test if the drinking water is clean. That’s why it’s important not to pour hazardous liquids onto the ground- they could end up in our drinking water!
NSF North Mississippi GK-8

17. NSF North Mississippi GK-8
Satellite Imagery
Satellite Imagery: Satellites orbit the earth and take pictures. It’s kind of like having a big map that can be updated very frequently. Many people use satellite imagery. Take a look and the next picture and you can see how much land is covered with trees, and how much is covered with homes. Geologists and other professionals can use this information to make decisions. For example, if someone wanted to build a new highway, where would be the best place to put it? By looking at a satellite image things like wetland could be seen and avoided much more inexpensively that sending a person out to look around. Show pictures of satellite imagery.
NSF North Mississippi GK-8

18. NSF North Mississippi GK-8

19. NSF North Mississippi GK-8
Geologic Maps
Geologic Maps: Geologic maps are different that road maps. They show the geologic features present at the surface. Each different soil and rock type is coded a different color. Geologists make geologic maps. First they go outside and make observations and then they use a computer to make maps. Show and example of a geologic map.
NSF North Mississippi GK-8

20. NSF North Mississippi GK-8
Tools Geologists Use
Compass
Maps
Rock hammer
Big machines for drilling
Hand lens
Dilute acid
Tools geologists Use: Geologists use a compass and maps to know where they are at all times when they are outside looking at rocks. Show examples of each. Explain that topographic maps are different from geologic maps because they tell elevation, not rock or soil type. They also use something called a rock hammer. This is a special hammer made to break off pieces of rock so that the geologist can take a closer look (show the example). When geologists collect core samples, they sometimes use big machines to drill very deep. Even though they can drill deep, they have not been able to drill through the crust yet. Geologists also use a hand lens, which is basically just a high powered very small magnifying glass (show the example). They use a hand lens to closely inspect and soil grain or rock features. They also use very diluted hydrochloric acid. There is a certain component of many rocks and soils called calcium carbonate. Calcium carbonate reacts with the HCl and fizzes. This helps geologists determine if the rock or soil contains calcium carbonate or not. Take out a sample of calcite and coquina. First drop a small drop of HCl onto the calcite and carry it around the room so the students can see and hear the fizz. Then show the coquina. Ask the students how a geologist might be able to figure what was cementing those shell fragments together. Then drop the acid on the sample. It will fizz. Explain that a geologist would immediately know that calcium carbonate was acting like the glue holding the shell fragments together.
NSF North Mississippi GK-8

21. NSF North Mississippi GK-8
Teamwork!
Teamwork: Teamwork is very important for any job that you get. Geologists work on teams with other scientists and engineers on almost every project. It is very important for them to be respectful and polite so the job can be completed quickly and safely.
NSF North Mississippi GK-8