Local Geology
General Stratigraphy Surficial geologic units overlying the area in and around the Crane Operation are predominantly comprised of undifferentiated Quaternary Age unconsolidated deposits, ranging from aeolian (windblown) sheet sands and dunes to alluvial sands, silts, clays, and caliche. Geologic mapping shows additional surficial stratigraphic units present in the vicinity of the project; however, the surface geology in and around the Crane Operation is primarily comprised of these aeolian sand deposits.

Exploration completed on the Crane property indicate two surficial sand units being present, an upper clean sand unit (dune and sheet sands) and an underlying clayey cover sand unit (Judkins Formation). The following text discusses the strata encountered in and around the Crane Operation, in depositional order:

-Fredericksberg Group A thick unit of limestone, dolomite, marl, and caliche, which represents the basal unit encountered at the Crane Operation. An unconformity separates this unit from the overlying Judkins formation, which differs significantly in age.

-Judkins (Blackwater Draw Equivalent) Formation The Judkins Formation is a brownish-red, argillaceous (clay-rich) sand body consisting of fine- to medium-grained quartz which may be silty and calcareous. This formation represents the first major period of dune building to affect the area and includes minor amounts of interdune pond sediments.

-Quaterna ........

The sheet sands and sand dunes in and around the Crane Operation are loosely consolidated and overlain by minimal overburden; characteristics which favor conventional surface mining techniques. Since the target sands formation does not extend below the water table, the quarry is ‘dry-mined’ using truck and excavator mining methods. Mining occurs in a series of benches arranged in a stair-like fashion to recover sand from the top of the formation (in elevation) down to the lowest practical elevation (generally 1 to 2 ft above the basal limestone unit).

In some areas of the deposit, the sand is overlain by up to 20 ft of caliche overburden which must be stripped prior to sand mining. An outside contractor is used to perform this work on an as needed basis. Generally, though, overburden at the Crane Operation is very thin and not stripped prior to sand excavation. Any vegetation, oversize material or clay that is present is removed at the processing plant using screens and scrubbers. Oversize material and vegetation are stored at the dry tailings stockpile for use in future reclamation.

Drilling and blasting are not required for the loosely compacted sand. Excavators and front-end loaders are used to load articulated haul trucks which transport the sand to a ROM stockpile near the wet process plant. Usually, the sand horizon is mined in a single 30-ft vertical bench. If the depth of the deposit exceeds 30 ft, a second lower bench is mined down to the top of ........

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