 The Muskeg Formation consists primarily of anhydrite, with dolomite, halite (rock salt) and limestone.The Muskeg Formation was deposited at the northern end of an embayment called the Elk Point Basin, adjacent to an extensive reef complex called the Presqu'ile Barrier.The reef had developed across the mouth of the embayment, blocking the area from the open ocean and restricting the inflow of sea water.