I would like to understand why drilling stopped at the depth it did. Was it something to do with the material at that depth, something to do with the drill, some other factor?
[0] https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#Drilli...
In other words I'm confused by why 180C stopped the drilling process.
At that depth, pressure and temperature, the rock behaved like plastic and not solid and the drill was ineffective since the hole would immediately close as they pulled the drill. So they had to give up.
Ninja-edit: It looks like the temperature / pressure isn't so problematic because of rock moving around, but instead to do with cooling the drill bit (which you can imagine gets quite hot). If temperatures increase, cooling the bit becomes difficult, and at high-pressures, pumping the coolant around becomes very difficult.
Source: https://geekswipe.net/research/engineering/how-deep-can-we-d...