If I was to tunnel straight through a mountain, what kind of rock would I find?

Question

I'm developing a semi-realistic game involving stereotypical dwarves digging into mountainsides and carving out grand caverns for themselves, similar to those in Moria or the Lonely Mountain from Tolkien's works.I'm attempting to research what kind of layers of rock (in layman's terms) you'd expect to find in a typical non-volcanic mountain range in say, northern Europe. So far though I'm at a loss so at this point anything would be a help!

Answer 1

In a nutshell, you would find lots of granitoids (all types of granitic rocks) and lots of metamorphic rocks. Metamorphic rocks are created due to high heat and pressure. The places we find high heat and pressure are places where our continental crust is the thickest, which is in mountain ranges. The average continental crust thickness is ~45 km. Places like the Himalayas and Andes have crustal thicknesses around ~70 km.