You cause the earth to ripple, triggering an avalanche of rock and stone to surge forward in a line 60 feet long and 15 feet wide. The length of the line is doubled if cast on a steeply sloped surface. Each creature caught in the surging tumble of rocks must make a Dexterity saving throw. On a failure, a creature takes 6d10 bludgeoning damage and is knocked prone. On a failure by 5 or more, it is stunned until the end of its next turn, and on a failure by 10 or more it is moved to the closest free space at the end of the line created by the spell. On a successful save, a creature takes half as much damage and suffers none of the spell’s other effects.   The spell creates a 15 by 15 foot area of difficult terrain at the end of the line created by the spell.