Determine whether the following disturbances will be followed by primary or secondary succession. In coastal areas, wind moves sand, blowing away or engulfing the soil, and eventually creating sand dunes: The introduction of livestock to an area leads to over-grazing that removes native grasses: A forest is cleared to gather lumber used for building houses: A lava flow down the side of a volcano destroys all vegetation and eventually turns into volcanic rock when it cools and hardens: