The smallest type of volcanoes are called cinder cones. Cinder cones often occur on the slopes or within the craters of other larger shield or stratovolcanoes. Cinder cones are composed completely of pyroclastic debris.
All right, so basically chunks of rock, ash that come out of this crater, they pile up and they form these small cones on other larger volcanoes. So they're built from this type of material. So these would be the cinders. These are basically ejected lava that is cooled very quick, that has holes left behind from gas that escaped as these things were flying out of the atmosphere. of the volcano through the air.
So this type of rock is called scoria. So it's a basalt with a very vesicular texture, so there was a lot of gas in that lava that escaped when it erupted. And essentially it's basically just a rock that was erupting from the volcano. just a pile of chunks of rock like this.
The entire central vent here is just filled in with these rock fragments. Then some of the lava can come up, it explosively erupts, and then it cools very quickly forming the scoria. Then that just piles up forming these small cinder cones.
So here's a typical cinder cone. They have very similar shapes no matter where in the world you see these things. They have these kind of steep sides with a very broad, deep, bowl-shaped crater in the center. Right. So lava does not tend to come out of the central crater here, because since this thing is just built up of loose rock particles, it's not actually strong enough to have lava be coming out and then like.
pouring out of the crater, like a stratovolcano or a shield volcano. So sometimes lava will seep out of the base. It'll make its way from that main conduit and then make its way under the piles of cinders and kind of squeeze out at the base. This is a volcanic bomb, so we talked about those in the stratovolcano video. This is a typical volcanic bomb.
They very often have this elongated shape because when that material is being thrown out of a cinder cone like this, or a stratovolcano, it's very very hot and so as it flies through the air it actually gets stretched out into this elongated form. So this would would consist of particles large and small of this pyroclastic material.