Burrow Speed

Burrow refers to the ability to move through the ground or other solid materials without being impeded. Burrow can be broken up into three general subtypes, however there may be others that are more unique to specific creatures.
Burrow: Creatures with this type of burrowing speed dig their way through the earth, moving unimpeded by soft ground and leaving behind disturbed earth but still what is considered solid ground. This means that unless another creature has a burrow speed, they can not follow a creature burrowing with this method. In addition they are unable to run or charge with this movement type.

Tunneling: Creatures with this type of burrowing speed are able to dig their way though soft and hard earth within reason. In addition they leave an obvious tunnel behind them that other creatures can follow through as long as they are the same or smaller size of the tunneling creature, if they are bigger they may have to make escape artists checks if they are able to attempt to follow at all. Just like with a burrow speed, a creature is unable to charge or run with this movement type.

Earth Glide: This movement speed is extremely rare and usually magical in nature as it allows the creature to meld with any unworked earth, rock, or stone and move through it completely unimpeded and without leaving any trace that the material had been moved through. In addition, if a creature has this movement type it also has the ability to see clearly through stone in some way, or at least target creatures. They are able to run and charge through the ground.