composite volcanoes don't just have a wand vent they have several inside they have a whole system of channels that bring up boiling lava from inside the earth when they erupt it's pretty violent with lava breaking through the sides of the volcano too due to the huge amount of volcanic material that can explode out of composite volcanoes they can be built up to enormous heights some of the world's most famous volcanoes are composite volcanoes including mount saint helens in america and japan's mount fuji from the air these volcanoes are wide and round making them look like yep you guessed it a shield this unique shape is produced by the thin runny lava that flows out of the volcano in times of activity shield volcanoes are what you might call slow burners they rarely erupt very dramatically and they take a long time to build up the volcanoes making up the hawaiian islands are shield volcanoes when the volcano erupts ash and lava are propelled out of the volcanic vent at the top the debris rains down around the vent and eventually cools down after several eruptions all of this material builds up the volcano into its cone shape but cinder cone volcanoes don't usually grow higher than one thousand feet