33 FIRST FLOOR EXHIBITS Nat ur al Cast of Dinosaur T r ac k Behind the migmatite is the natural cast of a dinosaur s hind footprint that flled with sand The sandflled trac k and the layer s below and abo ve it were buried compressed and cemented to form roc k Later they were uplif ted and eroded enough to be exposed at the surface The sandflled trac k has been preserved but the sof ter underlying layer s that originally held the footprint have been worn aw ay The sandstone cast now pro vides an upsidedown look at the ancient footprint Donated b y H Richard Blank Jr and Nanc y A Blank Kaesler in memory of their father Horace R Blank Sr who col lected the fossil in the late 1930s Cast of Dinosaur Skull While the origins of this skull cast are unknown it is nonetheless a perfectly ft ting unoffcial doorman that greets GS A employees as they ar ri ve in the morning and then bids them farewell as they leave eac h evening Giant Selenit e Crystal Enormous nearly fawless selenite crystals lik e this one are rare T aking its name from the Greek selenites moonstone this crystal w as found in 1 892 at the basal Entrada F ormation at Caineville Utah S elenite is a transparent variety of gypsum and is usually found with salts deposited along the edges of h yper saline shallow seas in arid climates It is especially common in roc k of P ermian T riassic and early J urassic ages across the Colorado Plateau The snow white dunes at White S ands National Monument in New Mexico are made of white gypsum sand Gift from the Department of Geolog y Brigham Y oung Univ ersity Pro v o Utah through Morris S P eterson T aking the stairs up to the right will lead you to the second foor exhibits listed on p 3742 The stairs going down lead to headquarters offces