Criteria Used for Classification of Mass-Movements
 1) Nature of materials:  e.g. Rocks vs. unconsolidated debris
 2) Speed of movement: from cm/yr to km/hr
 3) Nature of movement:
 a) sliding: bulk material moves as a unit.
 b) flowing: material moves as if it were a fluid.
 c) falling: materials detach and freely fall down
Applying these criteria we end with a coherent Classification of Mass Movements