The Rock Cycle

This week we began to learn about the rock cycle and the layers of the earth. We did a really cool lab to help us understand about how rocks are formed and we watched some videos and did some interactives on the layers of the earth and what causes earthquakes.

The Rock Cycle

There are three main types of rock, sedimentary, igneous, and metamorphic. Each rock has a different way to turn into that type and how to turn into another type of rock.

Sedimentary Rocks

Sedimentary rocks are made out of sediment. Sediment is little pieces of pebbles, rocks, fossils and sand that gradually accumulate and cement themselves into rocks. They take time, and sedimentary rocks are the only rocks that have fossils in them. They are quite crumbly and break easily.



Igneous Rocks

Igneous rocks are sometimes known as volcanic rocks. They are formed when magma within the earth or lava outside of the earth cools and hardens into rocks. This process happens so fast that no crystals can grow on the surface. Igneous rocks are smooth and glass-like with gas bubbles in them.



Metamorphic Rocks

Metamorphic rocks are formed underneath the earth when intense heat and pressure compacts layers of dust and rock into metamorphic rocks. This takes a really long time, so you can find crystals growing on them.



Metamorphic rocks can melt and harden to form igneous rocks, which can crumble up and become part of sediment, which can become compressed and form metamorphic rocks.

In our lab, we used candy to depict this. We were in partnerships, and each partnership had two Starburst candies. We were supposed to cut the Starbursts into little pieces (the smaller the better) for sediment. Then we would gently press the ‘sediment’ into a ball for a sedimentary rock. We recorded our findings.

We added lots of pressure with our hands to compress the Starburst sedimentary rock into a metamorphic rock. Once again, we recorded our findings.

Lastly, we placed our metamorphic rock in a paper cupcake cup and placed it into the microwave for 35 seconds. When we took it out, it was a liquid, but when it hardened, it had gas bubbles and a smooth surface. We had turned it into and igneous rock! The photo above at the very top is my igneous rock that I made with my partner. It was a cherry and lemon mixture, which tasted great as well.

We were also learning about the layers of the earth this week. There were the compositional layers, which included the crust, mantle, inner core, and outer core. Then there are the physical layers, which are the lithosphere, asthenosphere, the mesosphere, the outer core, and the inner core.

Compositional Layers

Crust

The crust is the thinnest layer of the earth; it is only 5-100 km thick. It includes the ocean floor and dry land, which is called the oceanic and continental crusts. It is made up mostly of silicon and oxygen in the form of granite and basaltic rocks.

Mantle

The mantle is the thickest layer of the earth, measuring 2,900 km thick. It is a semi-solid layer made up of silicate, iron, nickel, and magnesium. Magma that spews out of volcanoes comes from the mantle.

Outer Core

The outer core is a layer of liquid metal, mostly iron and nickel. It is 2,200 km thick.

Inner Core

The inner core is made mostly of iron and nickel as well. The pressure in it is so great that it becomes a solid ball. Its diameter is 2,456 km. When the outer core spins around it, the earth’s magnetism is created.

Physical Layers

Lithosphere

The lithosphere is about 15-300 km thick. It is cold and brittle, very easily broken. It is a combination of the crust and the upper region of the mantle.

Asthenosphere

The asthenosphere is the weak sphere. It is 250 km thick. It is a soft layer of hot semi-liquid that is constantly moving in convection currents (which will be explained later on). The plates of the lithosphere ‘float’ on the asthenosphere.

Mesosphere

The mesosphere is the middle sphere. It is the rest of the mantle that the lithosphere and the asthenosphere don’t take up, which is about 2,550 km. It is much stronger and hotter than the asthenosphere. It is a semi-solid, and it is believed that the pressure keeps it from flowing like a liquid.

Outer Core

The outer core is the only actual liquid layer of the earth. Although it is pretty much a superhot sea of iron and nickel, magma and lava DOES NOT come from here.

Inner Core

The inner core is the solid, dense core of the planet, a solid ball. The outer core’s rotation around it is what causes the earth’s magnetism. The earth’s inner core is hotter than the surface of the sun. The sun’s surface is about 5,500 °C. The inner core is about 6,000 °C. But the sun’s core is 15,000,000 °C, so the earth’s core is a lot colder compared to that.



https://rozsascience.files.wordpress.com/2013/01/the_earths_layers_foldable_completed.jpg

This is the foldable that we did in class to visualize this.

The convection currents are what cause earthquakes. The air gets hot from the inner core, and so it rises. Then is get cold from up there, so it sinks. This repeats around in there, sometimes causing the tectonic plates to shift.

S&EP:SP2, Using Models.

This week I learned a lot about the rock cycle and the earth’s layers because we made that foldable and did that lab. If those Starburst candies were actually rocks, it might have helped a tiny bit more, but that lab really helped to make sense of the rock cycle. And with the foldable we made, it showed all of the layers and what was going on.

XCC: Structure and Function.

If one of the earth’s layers wasn’t strong enough to support the other layers, the earth would completely fall apart. It is really important that everything is strong enough to support everything else and functions right to make everything okay.