Homeschool Earth Science Curriculum

When people hear the term Earth science, they naturally tend to picture the solid rock part of the planet we live on, as well as the huge bodies of water that cover about seventy percent of the Earth's surface. But when you get into Earth science, you realize how much there is to scientifically studying the Earth. As we discussed earlier, there are many different sciences that are part of the study of Earth science. Oceanography studies the oceans. Freshwater science looks at lakes and rivers. Paleontology studies past life forms. Meteorology studies the weather and other sciences that we'll study in our class. But today, we'll start our earth science discussion with geology, the study of what the earth is made of, what the earth looks like, and how the earth changes appearance over time. When it comes to studying what the earth is made of, that really means studying both the liquid rock and the solid rock that make up the earth. Now, I just said liquid rock, and most of us are familiar with solid rock that makes up the earth because we walk and drive on it and live on it every day. But there's also liquid rock underneath the earth's surface. We'll talk about this more in an upcoming class. But when we look at how the earth is built from the surface all the way down to its center, there are four main layers. As you can see from the labels, three of the layers are solid and one is liquid. That liquid rock layer is pretty deep down below the surface of the earth. So one aspect of geology is studying these layers of the earth and how they work. Another part of geology is studying the actual rock, studying the types of minerals that make up the rocks of the earth, and learning about the three major types of rock that the earth is made from. We'll get familiar with different landforms like mountains, valleys and plains, as well as general types of bodies of water like oceans, lakes and rivers. Understanding that the surface of the earth's appearance is constantly changing because of geological processes like weathering and erosion is another important aspect of geology, and we'll talk about those processes in our class. We can see a small example of how much the appearance of the earth can change in a short time with this picture of the Providence Canyon Outdoor Recreation Area in Georgia. Prior to about eighteen twenty five, this area was fairly flat and uniform, but likely had small depressions called gullies and maybe a slightly larger depression called a valley here and there. However, poor farming practices led to a lot of water runoff from farmers fields into and through this area, which over about fifty to sixty years in the 1800s eroded a lot of the soil and rock in this one thousand three acre area. That's about one and a half square miles so that there are many deeper gorges that are now up to about a hundred and fifty feet deep. This is just a small example of how quickly geological forces can change the earth's appearance. These easily visible changes of how the earth looks today instruct us that the earth of today doesn't look exactly like it did in the past. And whether a creationist or a naturalist, geologists or the scientists who study geology spend a lot of time trying to piece together how the earth's appearance has changed over time. Glaciers are another force that changed the way the earth looks, and we'll study them too. Now, before I end this brief introduction of where we're going in in the geology portion of our class, I want to orient you to the earth. And by that, I mean, let's review the basics about how the earth looks, because I'll be referring to this a lot throughout the course. The earth is a globe, a gigantic sphere like a ball, but it's huge about twenty five thousand miles all the way around, and there are seven major landmasses on it that are called continents. Australia, Asia, Europe, Africa, North America, South America, and Antarctica. Our study of geology will take us all over the Earth to all of the continents. And last for today is a brief mention of the location system that has been used for more than two thousand years, latitude and longitude. Those are the lines that maybe you have seen on the globe but didn't know exactly what they were. So north is here, south here, east is here, and west here. Latitude lines are the ones that go across the globe from east to west and look like the runs of a ladder. Latitude, ladder. Longitude are the lines that go from north to south. I don't have any cuter way to remember longitude. I just remember that the lines that don't look like the rungs of a ladder are longitude lines. The lines are numbered but I won't get into that too much now, but I do want you to know that the two lines where the numbering starts are the equator for latitude and the prime meridian for longitude. We'll learn a lot more about latitude and longitude later in the course, but that will do it for today.