Many of the more durable hoodoos are capped with a special kind of magnesium-rich limestone called dolomite. Dolomite, being fortified by the mineral magnesium, dissolves at a much slower rate, and consequently protects the weaker limestone underneath it in the same way a construction worker is protected by his/her hardhat. Rain is also the chief source of erosion (the actual removal of the debris). In the summer, monsoon type rainstorms travel through the Bryce Canyon region bringing short duration high intensity rain.