Ringold Formation

The Ringold Formation is a geological formation in Eastern Washington, United States. The formation consists of sediment laid down by the Columbia River following the flood basalt eruptions of the Columbia River Basalt Group, and reaches up to thick in places. It preserves fossils dating back to the late Miocene and Pliocene epochs of the Neogene period.
Exposures of the Ringold Formation can be found from Hanford Reach National Monument north to the Moses Lake area. Large portions of the formation are buried by other sediment deposits, extending as far as Wallula Gap southeast of Kennewick. In recent years, irrigation water entering the groundwater system has destabilized some Ringold Formation slopes and cliffs, causing landslides. The formation was named in 1917 for a school of the same name that existed at the time. Ringold School was located on the Franklin County side of the Columbia River to the south of Savage Island.

Geology

During the flood basalt eruptions before the sediments were laid down, the Columbia River followed a different route than it does today, taking it near the present-day sites of Yakima and Goldendale. North-to-south compression of the Columbia Plateau caused anticline folds like Rattlesnake Mountain and the Horse Heaven Hills to rise.
These ridges provided geographic barriers, rerouting the river eastward toward the Tri-Cities with it eventually flowing through Wallula Gap. During part of this period, the Columbia River was completely dammed leading to the development of a large lake covering the Yakima Valley and southern Columbia Basin. The Ringold Formation is the sediment laid down during the period of the lake's existence and while the route of the river was changing.
Some of the sediments found as part of the formation may have been sourced from ancestral versions of other Pacific Northwest rivers like the Clearwater and Pend Oreille. Layers of volcanic ash can also be found, with thicknesses ranging from being barely noticeable to thick.

Stratigraphy

The Ringold Formation represents sand and gravel placed by the Columbia River between around 8.5 and 3 million years ago. These deposits overlay cooled lava erupted as part of the Columbia River Basalt Group, a type of volcanic eruption known as flood basalts erupting from fissures across eastern Washington and Oregon that were unrelated to the Cascade Range. It is covered in places by deposits from the Missoula Floods.
Regional uplift caused the Columbia to erode parts of the Ringold Formation. The White Bluffs on Hanford Reach National Monument are a significant example of this.

Recent landslides

Landslides along the Columbia River have increased in recent years due to irrigation around Basin City and Othello. Irrigation water enters and flows through the groundwater system toward the river easily through deposits left by the Missoula Floods. This destabilizes Ringold Formation features like the White Bluffs, causing the landslides. Landslides did not occur frequently before 1960. Rapid changes in river flow caused by the Priest Rapids Dam upstream may also contribute to slope destabilization.
The largest landslide in the White Bluffs portion of the formation is adjacent to Locke Island. This complex, initiated in the 1970s, has rerouted the Columbia River. As a result of the change, critical salmon spawning habitat has been destroyed. The landslide restricts the flow of the river on the east side of the river and as a result, large portions of Locke Island are being removed by the Columbia River. Movement of this landslide is ongoing, but the primary factor behind the continued movement is destabilization by the Columbia River eroding the fallen material. Blown sand from this landslide is the primary source material for sand dunes atop the bluffs near the island.
The Locke Island slide is the northernmost slide along the White Bluffs. There are at least five other major slides into the Columbia River, with the southernmost one being across the river from Pacific Northwest National Laboratory in north Richland, which occurred in 2008. At least one slide has occurred in nearby coulees.

Paleobiota

Mammals

The mammal fossils of the Ringold Formation are divided into several local faunas, from youngest to oldest:Taunton local fauna Blufftop local fauna White Bluffs local fauna

'''River Road local fauna'''

Amphibians

Indeterminate frog or toad bones are known from the White Bluffs local fauna.

Invertebrates

Several species of freshwater snails are known from the White Bluffs local fauna.

Plants and climate

Pollen has been sampled from the lower Ringold Formation near Hanford, as well as the upper Ringold Formation at White Bluffs. The lower Ringold flora is similar to moist eastern ecosystems such as the Mississippi lowland forests, where cypress and broadleaf hardwoods coexist in close proximity. Pollen from White Bluffs corresponds to semi-arid grassland plants such as grasses, saltbush-type plants, and sunflower-type plants, alongside rare pine pollen.
Warm-water fish and tortoises suggest that the fossil-rich Pliocene portion of the formation probably had hot summers and mild winters. In warmer parts of the Pliocene, winters may have been entirely frost-free. Pike and sturgeon may indicate the presence of deep, persistent streams. Other studies estimate a yearly rainfall not exceeding, still much greater than the modern Columbia Plateau. Riverside floodplain environments were far more common than today, supporting a greater diversity of mammals and wetland inhabitants.