Lava domes

A lava dome is a structure composed of extremely viscous lava with a typical dome shape.
Schema di formazione di un duomo lavico
They form because of the high viscosity of the lava which, leaving the ground at relatively low temperatures of 600/800 °C, is therefore nearly all already solidified and cannot flow.
For this reason the domes are imposing structures in which, unlike other lava morphologies, the height is almost equal to the distance travelled by the lava.