The reasons are mean, the place where pluto lives has its own rules, it is very cold here, water ice becomes bedrock.
It gets frozen harder and meaner than stone on Earth. It is a place of giants mountains, jagged blocks of this water ice-They are not pushed up by colliding continents.
Frozen nitrogen, a great flat sea of it.
A glacier. A thing called Sputnik Planiti. A moving sheet of softer ice-puts great heft on the edges of its basin.
It shoves against the water ice crust-A thing that is unyielding, cracks and pushes colossal blocks miles into cold air.
There are other peaks.
Great mean mounds on the plains, these things are likely cryovolcanoes-They spew a slushy, icy mix from gut of Pluto, no hot lava.