McKinney Falls State Park fossiliferous limestones

McKinney Falls State Park sits on Cretaceous limestone bedrock and exposes fossiliferous layers along Onion Creek and the park’s falls where shell fragments and other marine fossils occur within the rock. Park geological information and field guides note visible fossil-bearing limestone outcrops at the park that reflect Central Texas’ Cretaceous marine history. These outcrops are commonly cited in regional descriptions of Austin-area fossil beds.