Sage: In the wilds of Chile, there are mountains that look like Oreos?
These are Los Cuernos del Paine. Their unusual appearance draws thousands visitors every year. With a thick light stripe between two dark layers, they out here looking like a snack.
But besides looking cool, they actually have a lot to teach us about geology's star subject. That's right, it's the rock episode.
Hit it, Dwayne! [Dwayne with guitar attached]
Hi, I'm Sage, and this is Cras Course: Geology. [Theme music]
Los Cuernos are amazing not just for their unique visual features, but because they showcase every part of the cycle.
[Dwayne with guitar] Listen, Dwayne, if you do that every time I say rock in this episode, we'll be here awhile. Just turn it — just turn it down a little bit, pal.
The rock cycle is a process that recycles Earth's raw materials over time.
The rock cycle makes it possible for any kind of rock to transform into another kind of rock. It's one of the forces that continuously freshen up Earth's surface.
It's the reason why when you hold a rock in your hand, you're not holding something that's frozen in time forever. A rock's current identity isn't what it once was or what it'll be in the future.
But first, what really is a rock?
Stonehenge, the Blarney Stone, Emma Stone. Since the dawn of time, rocks have held many meanings for many peop— What? We don’t have that much time? What am I supposed to do with these? [Holding up fanny pouch and string of pearls] [Card with Dwayne saying, "Things got a bit rocky. Please stand by."]
[Wearing fanny pouch over the shoulder] As I was saying, in geology, the word rock has a specific meaning, a solid cluster of one or more minerals.
Minerals, by the way, are solid crystals with a specific chemical composition formed by geological processes.
Dwyane, one of us is going to have to change. [Dwayne is wearing fanny pouch just like Sage's] Ugh! Stubborn as a rock. [Card with Dwayne saying, "Things got a bit rocky. Please stand by."] [Sage is no longer wearing the fanny pouch]
I think a rock's kind of like dogs. You have your pure-breds, like quartzite, which is mostly just the mineral quartz. Then you got your mutts, which are a mix of different minerals.
Like Dwayne is granite, which is mostly quartz, feldspar, and mica, but can also have a lot of other minerals like hornblende, zircon, magnetite.
But even mutts still fall into 3 basic types, classified by how they formed within the rock cycle: sedimentary, like this sandstone; igneous, like this beautiful basalt; and metamorphic, like this nice, well, gneiss.
All three of these rock types were involved in the formation of Los Cuernos.
Let's start at the bottom. Rock bottom, am I right? I think I just have to accept the puns at this point.
Like Dwayne is granite, which is mostly quartz, feldspar, and mica, but can also have a lot of other minerals like hornblende, zircon, magnetite.
But even mutts still fall into 3 basic types, classified by how they formed within the rock cycle: sedimentary, like this sandstone; igneous, like this beautiful basalt; and metamorphic, like this nice, well, gneiss.
All three of these rock types were involved in the formation of Los Cuernos.
Let's start at the bottom. Rock bottom, am I right? I think I just have to accept the puns at this point.