>>48122866>Rock type became separate from groundRock and Ground were always separate.
Ground in gen 1 was mostly a designation for big, bulky land pokemon or burrowers who had the power to shake or move the earth, where as rock was more of an elemental designation for Pokemon composed of actual rock.
This is similar to how Water is mostly fish Pokemon with only a few water elementals strung about where as Ice is mostly composed of ice elementals with only a few "pokemon that live in the cold" strung about
