Enrichment: Cinder Cone Volcanoes
Many volcanic eruptions produce small cinder cones. These may form on the flanks of a shield volcano (such as are shown in the picture of Mauna Kea), or a stratovolcano, or in other volcanic settings such as where a spreading ridge comes above sea level. Cinder cones form when a small opening reaches the surface above magma containing gas. If you have ever been really close to a recently poured carbonated beverage, you know that the bubbles rise and then break, throwing droplets of the drink that can make your face wet. Similarly, bubbles rise and break in the melted rock, throwing droplets that freeze in midair, and then fall as loose pieces that pile up around the opening. Walking up a cinder cone can be difficult because the loose pieces roll easily underfoot.
Cinder cones are not as important as other volcanoes in making large mountains that last a long time, but many people have seen a cinder cone, and sometimes they can be dramatic. Back in 1943, a new cinder cone suddenly began growing in a cornfield west of Mexico City. The volcano Parícutin grew to be more than 1300 feet (400 m) high, buried two towns, and killed three people, but eventually quit erupting and became a great tourist attraction.
Watch some short vintage videos discussing cinder cones.
Video: Cinder Cone Volcanoes: Sunset National Park #1 (1:14)
An explanation of cinder cone volcano formation by CAUSE student Sam A.
CAUSE Student: Right now we're at-- this is called Lenox Crater, and it's a volcano. It's a cinder cone volcano. If you looked around behind us, right at the center there's a big crater, hence the name. And all the stuff that we're sitting on right here is cinders, basalt rock that was ejected from the volcano. And as it was ejected, it was thrown up and out, kind of like this. And--
Kind of like what?
[LAUGHTER]
CAUSE Student: Kind of like that. And it just over the years built up and built this-- what did it say, it's 400 feet high or something like that? Yeah. Not too bad.
Video: Cinder Cone Volcanoes: Sunset National Park #2 (2:09)
Another, slightly "dramatized" explanation of cinder cone volcano formation by CAUSE students Stephanie S. and Raya G.
Ryan, CAUSE Student: That was hard. Why?
Stephanie, CAUSE Student: Well, Ryan you just walked up a really steep side of a volcano.
Ryan: What volcano?
Stephanie: This volcano.
Ryan: That's a volcano?
Stephanie: Yeah. Right over there's the center of the volcano. And we're sitting on top of cinders that were thrown out of the volcano.
Ryan: What's a cinder?
Stephanie:These are cinders.
Ryan: What are they?
Stephanie: OK, imagine this is the bottom of the volcano. Stuff's thrown out of the center of the volcano. And it starts to build up around the side. So eventually, when enough stuffs thrown out, you get a steep-sided volcano. It's just layer, upon layer, upon layer, upon layer, upon layer of stuff that's ejected out of the volcano, falling down on top of each other.
Ryan: How far does cinder travel?
Stephanie: Well, we're sitting about a quarter mile from the center of the volcano, so these cinders traveled about a quarter mile. They can go further than that, a mile.
Ryan: So if this is cinder, it's so small. I mean, are they all this small?
Stephanie: Yeah. Well, some are real small, some are a little small. Some are big, and some are the size of Volkswagens.
Ryan: Oh. But Stef, I still don't get it. I mean, where else are we going to see this in the real world?
Stephanie: Have you ever made spaghetti?
Ryan: Yeah.
Stephanie: All right. Well, think of a pot of spaghetti sauce. You've got the heat cranked up real high, and the sauce starts boiling. You get bubbles and then, next thing you know, you've got butter and spaghetti sauce. You've got spatters of sauce all over your kitchen stove.
Ryan: And that's exactly what's going on over here?
Stephanie: Yeah. Why don't we go to take a look?
Ryan: OK.
Stephanie: Go down in the crater.
Ryan: Hey!
Video: Cinder Cone Volcanoes: Sunset National Park #3 (1:07)
A third explanation of cinder cone volcano formation, by Dr. Alley himself.
Dr. Richard Alley: We're looking at Sunset Crater, a volcano that erupted almost 1,000 years ago. It's primarily a cinder cone, so when it was erupting it was sort of spitting out little pieces like a pot of spaghetti sauce bubbling and throwing things.
Those little pieces-- we can actually see similar pieces from either that one or a different eruption here. And we've been walking on them, and they're not terribly pleasant for walking on, but you can build a pile out of stuff like this. There's probably lava flows helping to hold that one up.
A little more oxidized late in the eruption, and so you get that pretty red around the top that gives the Sunset Crater name.