Soften earth and stone

Soften earth and stone is a transmutation spell turns stone to clay or dirt to sand and mud.

Effect
When this spell is cast, all natural, undressed earth or stone in the spell's area is softened. Wet earth becomes thick mud; dry earth becomes loose sand or dirt; and stone becomes soft clay that is easily molded or chopped. You affect a 10-foot-square area to a depth of 1 to 4 feet, depending on the toughness or resilience of the ground at that spot (DM's option). Magical, enchanted, dressed, or worked stone cannot be affected. Earth or stone creatures are not affected.

Creatures in mud must succeed at Reflex saves or be caught for 1d2 rounds and unable to move, attack, or cast spells. Creatures who succeed at their saves can move through the mud at half speed, and they can't run or charge.

Loose dirt is not as troublesome as mud, but all creatures in the area are reduced to half their normal speed and can't run or charge over the surface.

Stone softened into clay does not hinder movement, but it does allow characters to cut, shape, or excavate areas they may not have been able to affect before. For example, a party of adventurers trying to break out of a cavern might use this spell to soften a wall. While soften earth and stone does not affect dressed or worked stone, vertical surfaces such as cliff faces or cavern ceilings can be affected. Usually, this causes a moderate collapse or landslide as the loosened material peels away from the face or the wall or roof and falls.

A moderate amount of structural damage can be dealt to a manufactured structure (such as a wall or a tower) by softening the ground beneath it, causing it to settle. However, most well-built structures will only be damaged by this spell, not destroyed.