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.
A root barrier or root wall is a durable barrier that effectively stops unwanted tree and plant root damage to foundations, pavement, driveways, sidewalks, and other infrastructures. Trees are responsible for over 50% of foundation problems.