The Upper Cretaceous Iron Springs Formation in southwest Utah consists of 1,000 m of fluvial sandstone, conglomerate, mudstone, and minor lacustrine carbonate rock. The formation was deposited in the proximal reaches of the southern sector of the Sevier foreland basin. These strata record uplift and erosion of thrust sheets in the fold/thrust belt to the west.

Facies associations indicate deposition in alluvial fan and fluvial braidplain environments. Laterally extensive sheets of clast-supported cobble conglomerate were deposited during episodes of unconfined sheetflood flow. Mud matrix-supported boulder conglomerate represents locally derived muddy debris flows. Lenticular bodies of sandstone and conglomerate were deposited...