In geology, the term Torridonian is the informal name for the Torridonian Group, a series of Mesoproterozoic to Neoproterozoic arenaceous and argillaceous sedimentary rocks, which occur extensively in the Northwest Highlands of Scotland. The strata of the Torridonian Group are particularly well exposed in the district of upper Loch Torridon, a circumstance which suggested the name Torridon Sandstone, first applied to these rocks by James Nicol. Stratigraphically, they lie unconformably on gneisses of the Lewisian complex and their outcrop extent is restricted to the Hebridean Terrane.
The Roxbury Conglomerate, also informally known as Roxbury puddingstone, is a name for a rock formation that forms the bedrock underlying most of Roxbury, Massachusetts, now part of the city of Boston. The bedrock formation extends well beyond the limits of Roxbury, underlying part or all of Quincy, Canton, Milton, Dorchester, Dedham, Jamaica Plain, Brighton, Brookline, Newton, Needham, and Dover. It is named for exposures in Roxbury, Boston area.
The Unkar Group is a sequence of strata of Proterozoic age that are subdivided into five geologic formations and exposed within the Grand Canyon, Arizona, Southwestern United States. The 5-unit Unkar Group is the basal member of the 8-member Grand Canyon Supergroup. The Unkar is about 1,600 to 2,200 m thick and composed, in ascending order, of the Bass Formation, Hakatai Shale, Shinumo Quartzite, Dox Formation, and Cardenas Basalt. Units 4 & 5 are found mostly in the eastern region of Grand Canyon. Units 1 through 3 are found in central Grand Canyon. The Unkar Group accumulated approximately between 1250 and 1104 Ma. In ascending order, the Unkar Group is overlain by the Nankoweap Formation, about 113 to 150 m thick; the Chuar Group, about 1,900 m (6,200 ft) thick; and the Sixtymile Formation, about 60 m (200 ft) thick. These are all of the units of the Grand Canyon Supergroup. The Unkar Group makes up approximately half of the thickness of the 8-unit Supergroup.
The Wentnor Group is a group of rocks associated with the Longmyndian Supergroup of Precambrian age in present-day Wales, U.K.
The Stretton Group is a group of rocks associated with the Longmyndian Supergroup of Ediacaran age, in Shropshire, England. The rocks are located within the tract between two elements of the Welsh Borderland Fault System, the Church Stretton Fault and the Pontesford-Linley Lineament.
The Abiquiu Formation is a geologic formation found in northern New Mexico. Radiometric dating constrains its age to between 18 million and 27 million years, corresponding to the late Oligocene to Miocene epochs.
The Tesuque Formation is a geologic formation in north-central New Mexico. The formation provides an unusually complete record of the evolution of mammals during the Miocene epoch.
The Palm Park Formation is a geologic formation in southern New Mexico. It preserves fossils dating back to the Eocene epoch.
The Semilir eruption was a major volcanic event which took place in Indonesia during the Early Miocene. This eruption formed Semilir Formation and Nglanngran Formation. These two geological formations are in Southern Mountains of East Java. The eruption created two formations consists mostly pyroclastic rock. It has incredibly thickness. In contrast, Toba eruption only formed 600 m (2,000 ft) ignimbrite. Semilir eruption age date by isotope method is 21 million years ago.
The geology of the Northern Mariana Islands began to form with undersea volcanic eruptions in the Eocene. Islands such as Saipan show a variety of rock types including volcanic rocks, breccia, tuff, conglomerate, sandstone, clay and extensive limestones.
The Espinaso Formation is a geologic formation in New Mexico. It has a radiometric age of 34.6 to 26.9 million years, corresponding to the late Eocene through Oligocene epochs.
The Tanos Formation is a geologic formation in central New Mexico. It is estimated to be about 25 million years in age, corresponding to the Oligocene epoch.
The Polvadera Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 13 to 2.2 million years, corresponding to the Miocene through early Quaternary.
The Keres Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 13 to 6 million years, corresponding to the Miocene epoch.
The Tewa Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 1.85 million to 72 thousand years, corresponding to the Pleistocene epoch.
The Servilleta Basalt or Servilleta Formation is a geologic formation that underlies most of the Taos Plateau of northern New Mexico. It has a radiometric age of 3.6 to 4.5 million years, corresponding to the Pliocene epoch.
The Hinsdale Formation is a geologic formation exposed in southwestern Colorado and northern New Mexico. It has a radiometric age of 4.4 to 26.8 million years, corresponding to the Neogene period.
The Love Ranch Formation is a geologic formation in southern New Mexico. It was likely deposited during the late Paleocene and early Eocene epochs.
The Bell Top Formation is a geologic formation in southern New Mexico. Radiometric dating of surrounding tuffs indicate that it was deposited in the Oligocene epoch.
The Vasquez Formation (Tvz) is a geologic formation cropping out at the eponymous Vasquez Rocks in southern California. The formation dates to the Late Oligocene to Early Miocene.
