Volcanoes!
Here is a sample volcano. Volcanoes have magma chambers where magam makes its way to the  surface.
Magma flows through vents. When a vent leads to the surface magma, now lava, can flow down the side 
of the mountain. If magma gets trapped the heat can cause gasses to create pressure enough to explode out
of the volcano. Such eruptions can create craters along with ash fall.
Aside from hotspots, volcanoes are formed
at tectonic plate boundaries. Divergent boundaries
have fewer volcanoes form than convergent 
boundaries. Massive plates subducting into the 
mantle create chains of active volcanoes like at 
the Ring of Fire!
Strato cones or composite cones
are very recognizeable because
they form huge volcano mountains.
Mt Saint Helens is an example of a 
composite cone volcano that forms
from explosive ashes and cinders as 
well as lava flows.
Here's Mt Saint Helens.
Composite Volcanoes 
can really erupt!
Cinder cones erupt 
explosively all the 
time! They are built up
by ash and cinders.
Here's a sample
of how a cinder cone
volcano is formed.
Shield volcanoes are the most 
spectacular! The Hawaian islands
are the most famous shield volcanoes.
They are formed my flowing lava!
Fast Flowing, super hot lava!