Today, we’re going to learn about sedimentary rocks!
There are three main types of rocks: igneous, metamorphic, and sedimentary.
Igneous rocks are: formed from magma or lava and are found at the Earth’s crust.
Metamorphic rocks are: formed from high temperature and/or high pressure.
A metamorphic rock is created by changing or “morphing” another existing rock into something new.
Sedimentary rocks are: formed from layers of sediments at the Earth’s surface. This is what we are focusing on today!
Think about the word sediment… does it mean anything to you? Brainstorm what sediment might mean or what the word sediment reminds you of.
Sedimentary rocks are formed over time at the Earth’s surface by a variety of processes (air, ice, water, wind, and/or gravity). You might find sedimentary rocks close to the ocean, for example. Waves and bodies of water cause different materials to wash ashore and form layers and layers of deposited particles. As layers are added, pressure increases. Over time, these layers get compressed from loose sand, pebbles, minerals, or seashells into hard layers of rock. When rocks form this way, it's called lithification.
Which layers are the newest? Why?
When you see sedimentary rocks, you may notice different textures and colors. This is because they have been formed over a long period of time from many different materials.
YOU WILL NEED:
* Puffed rice or rice crisp cereal
* Caramel or chocolate chips
* Toppings (any kind of candy, chocolate or popcorn will do)
* Rubber spatula
* Baking Pan
Here’s what to do!
1. Melt 2 tablespoons of butter in a saucepan over low heat.
2. Add 2 cups of marshmallows and stir over low heat until the butter and marshmallows form a fluffy sauce.
4. Spread your first layer of marshmallow cereal into the baking pan. Pack it down! Remember, this is your oldest sedimentary layer, so it should be very firm since it’s been under all that pressure!
10. Cut your bars apart and enjoy! Make sure to pay attention to all the different layers you’ve created!