induration. 1. the process of hardening or being hardened.
1 They're weak against the Ice and Water types in reference of erosion, which cause this elements to the ground. 2  They're immune against the Electric type because in real life, the ground is a natural sink of electrons.  The Bug type resists them because many bugs like worms live inside the ground and many of them eat it.
Defense. The Rock type is rather risky defensively. Tied with Grass, Rock types have the most weaknesses of any type, with five. The fact that Rock-types on average have mediocre Special Defense makes it harder to survive against its weakness to Grass-and Water-type moves, which are typically Special in nature.ied with Grass, Rock types have the most weaknesses of any type, with five. The fact that Rock-types on average have mediocre Special Defense makes it harder to survive against its weakness to Grass-and Water-type moves, which are typically Special in nature.