Why is Earth is the omnipresent conductive surface?

Answer 1

Water in soil, water in streams, water in ocean are conductors. Ions easily flow. This makes for an excellent reference level, or "ground" as we have named it. There is no mistake in calling it ground, as it does conduct easily. Now some Earths are not all that great. Under my HF radio tower, on a sheet of rock..that is a terrible ground plane, so wires are strung under the soil radially, to simulate a ground so the radio wave can propagate radially. http://www.sgcworld.com/Images/Technical/radialarray1.jpg