Complex sentence: At the southern limit of its outcrop the Cottonwood Limestone is a medium crystalline limestone with thin, shelly layers; molluscs, Osagia, and quartz silt are common (silty Osagia facies).
Split into simpler sentences: At the southern limit of its outcrop the Cottonwood Limestone is a medium crystalline limestone with thin, shelly layers. Mollusks, Osagia, and quartz silt are common (silty Osagia facies).