Source: Races of Stone
You are in tune with the earth beneath you.
Prerequisite: Con 13, Wis 13
Benefit: As long as you are touching the ground, you can take a move action to sense the number of creatures within 20 feet that are also touching the ground and the direction to each one. You cannot pinpoint the location of any creature with this feat.
Special: Creatures with the air or aquatic subtype may not select this feat.