[RightWhale]

There has been and continues to be a continuous overlay of micrometeorite dust over the entire planet. In the course of a few megayears this is a substantial amount of new material. If we could strip the top ten feet of soil off the entire planet, what would we find? In some places airborne sediment is a lot more than this.

[blam]

"In some places airborne sediment is a lot more than this."

Yup. I've read that (the) Ukraine has a topsoil depth of 150 feet. It blew in there over the eons from other places.