A cinder cone volcano has a crater-shaped opening. The crater opening is unique to this type of volcano because of the type of eruption. A vent in the ground is created by the explosion of magma breaking through the crust and becoming lava. The lava then flows over the edge of the vent. The crater is created when the flow of lava ceases and cools, creating a higher ring around the fissure opening.
The central vent is the main opening inside the crater. This vent is connected to the conduit or pipe that travels from the top of the volcano to the underside of the tectonic plate. The conduit brings the magma up from the layer of Earth in which it flows to the surface. Until pressure is built up enough to break through the ground, the magma sits in the conduit. The breach in the ground is the vent through which the magma flows turning into lava, gas and ejecta.
The magma turns into lava, gases and ejecta. Lava is molten rock and ejecta is rock fragments from previous layers of the volcano that have not completely melted. These fragments are only partially molten and have a solid shape. As they fly through the air during an eruption, the coolness of the air solidifies the melted parts of the rock. The larger, molten ejecta are called bombs because they are hot enough to burn if they land on something flammable.
A cinder cone volcano is called such because the ejecta looks like cinders. Cinders are igneous rocks with a multitude of cavities or holes. The holes are created by the gases that are caught inside the magma as it bubbles inside the conduit of a volcano. The rocks fly out of the volcano when it erupts and the gases are released. As the rock cools, the spaces where the gas was released are frozen into the rock, causing the holes. The cinder then falls down around the vent, creating the cone of the volcano.