Through the passage of more millenia the continents wander, colliding. The collision forces hardened magma into the sky. It loses its dark overburden through yearly cycles of freezing and heat, rain and snow. What's left is very competent rock, but the forces of moving landmasses don't stop. Water intrudes, year by year dissolving and working its way in deeper.
Earthquakes shake the mountains of shattered bright rock and pieces tumble.
Other cycles overlay the geologic ones. Year by year people follow their tracks through various harvests. Trade routes work through the sharp mountains. Harvesters gather acorns, chia seeds, pine nuts and anything else. In a place like this one can't be choosy.