The Glen Rose Formation is a Lower Cretaceous rock unit spread across central Texas, deposited in shallow seas and shoreline environments about 115 to 105 million years ago. As the uppermost and most widely exposed part of the Trinity Group, it helped shape the region’s stair-step hills through alternating limestone and marl layers. It is most famous for abundant dinosaur footprints, especially along the Paluxy River near Glen Rose, where scientifically documented sauropod and theropod trackways became some of North America’s best known. Rich in marine fossils and important to modern groundwater systems, it remains one of central Texas’s most significant geologic formations.