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Show Minerals and Hydrocarbons Introduction The state owns the minerals located in the bed and waters of GSL as public trust resources. The responsibility to manage the minerals of the lake, and of all sovereign state lands, has been assigned to the DFFSL by statute. The division has specific management responsibilities for minerals of GSL pursuant to Section 65A- 10- 18 of the Utah Code. Internal and external scoping conducted by the planning team focused on the DFFSL MLP categories and policies. Although GSL is renowned for its " salt" ( sodium chloride or table salt), its waters actually contain other sodium, potassium ( potash), calcium and magnesium salts. GSL contains salt from a variety of sources. Rain and snow in the mountains leached saline materials from soils and rocks and carried it in solution to streams that eventually flow into the lake ( Miller, 1949). GSL may be as salty as it is because much of the salt was originally in the waters of Lake Bonneville and was concentrated as those waters evaporated ( Trimmer, 1998). In addition, some believe that the lake's salts were leached from deposits of oceanic salt of Jurassic age which crop out extensively in Sanpete Valley within the GSL Drainage Basin ( Eardley, 1938). Due to the terminal nature of GSL, salt delivered to it remains in the lake. Water entering the lake escapes by evaporation only. GSL presently contains 4.3 billion tons of salt in its system ( Trimmer, 1998). Other geological resources under and around the lake include mirabilite and epsomite, oil and gas, oolites and quartzite. Oil has been produced at Rozel and West Rozel Point oil fields and natural gas has been produced at Farmington Bay and Bear River Bay but commercial quantities of hydrocarbons have not yet been discovered. Mirabilite and Epsomite The most economically important salts in the lake are table salt, potash and magnesium chloride but mirabilite and epsomite are significant resources which have been produced from the lake. Mirabilite ( sodium sulfate) is a mineral that is precipitated from highly concentrated lake brines during the cold winter months. This salt is not stable and redissolves as the brine warms in the spring except where it is enclosed in sediment at the bottom of the lake. During the construction of the northern railroad causeway in about 1900, a deposit of mirabilite was discovered west of Promontory Point. Eardley ( 1963b) described the deposit as lying 15 to 25 feet below the bottom of the lake, interbedded with the soft lake- bottom clays, and having a maximum thickness of about 32 feet. The salt bed extends westward about 9.5 miles from a point one mile west of Promontory Point, and is bounded on the east by a fault. When the pilings were driven during construction of the old Saltair resort on the southern end of the lake, a hard layer of mirabilite- cemented oolites was encountered. This layer was penetrated only by steam- jetting a hole for the pilings. Soon after the pilings were installed, natural recrystallization of the 119 |