Answer and Explanation:
As can be seen in the description above, gneiss has gone through regional metamorphism. This means that this rock has been subjected to very high temperature and pressure. This triggered a series of chemical transformations in the minerals that this rock presented that had a certain resistance to high temperature and pressure, which prevented them from breaking and promoting the breaking of the rock. However, these minerals showed strong ductility, which caused them to deform their structures, allowing the gneiss to fold, until the temperature and pressure dropped.
