Red beds in the context of Selja Gorges

The Red River is a major river in the Southern United States. It was named for its reddish water color from passing through red-bed country in its watershed. It also is known as the Red River of the South to distinguish it from the Red River of the North, which flows between Minnesota and North Dakota into the Canadian province of Manitoba. Although once a tributary of the Mississippi River, the Red River now is a tributary of the Atchafalaya River, a distributary of the Mississippi that flows separately into the Gulf of Mexico. This confluence is connected to the Mississippi River by the Old River Control Structure.

The south bank of the Red River formed part of the US–Mexico border from the Adams–Onís Treaty (in force only in 1821), until the Texas Annexation and the Treaty of Guadalupe Hidalgo.

The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.902 Ma and 246.7 Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era. It is preceded by the Lopingian Epoch (late Permian, Paleozoic Era) and followed by the Middle Triassic Epoch. The Early Triassic is divided into the Induan and Olenekian ages. The Induan is subdivided into the Griesbachian and Dienerian ages and the Olenekian is subdivided into the Smithian and Spathian ages.

The Lower Triassic series is coeval with the Scythian Stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, a lithostratigraphic unit of continental red beds.