How far into the Earth will earthworms tunnel?

Question

I know that they are found in all layers of soil, I just need to know how far into the earth they have been found, and which, if any, parts of the world have no worms?

Answer 1

I don't know how deep they'll go, but since they feed on organic matter, I would imagine that they don't go too deep, except in the winter time to avoid frost.
The northern parts of Canada don't have worms. They all perished in the last ice age, about 12,000 years ago, and have only slowly been making a comeback since then. Since worms travel slowly and rather randomly through the soil, they make very slow year-over-year progress into the northlands.