Toreva block

   A slump block consisting of a single large mass of unjostled material which, during descent, has undergone a backward rotation toward the parent cliff along a horizontal axis that roughly parallels it; a type of rotational landslide. The unit forms a crude, elongated rectangular block rather than a bowl shape or chaotic mass; typically associated with horizontal to gently dipping sequence of coherent bedrock such as sandstone, which overlies a less coherent bedrock formation such as clay shale which is prone to slumping (e.g., southern Black Mesa area, AZ).

   SW, GG, & RF