The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359. 2 ± 2. 5 Ma ( million years ago ), to the beginning of the Permian Period, about 299. 0 ± 0. 8 Ma.

The Cretaceous (, ), derived from the Latin " creta " ( chalk ), usually abbreviated K for its German translation Kreide ( chalk ), is a geologic period and system from circa to million years ( Ma ) ago.

In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the Cenozoic era.

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416. 0 ± 2. 8 Mya ( million years ago ), to the beginning of the Carboniferous Period, about 359. 2 ± 2. 5 Mya.

* Epoch ( geology ) or geologic epoch, a span of time smaller than a " period " and larger than an " age "

In natural science, there is need for another time perspective, independent from human activity, and indeed spanning a far longer period ( mainly prehistoric ), where geologic era refers to well-defined time spans.

The Jurassic is a geologic period and system that extends from Ma ( million years ago ) to Ma ; that is, from the end of the Triassic to the beginning of the Cretaceous.

In North America, where the interval consists primarily of marine limestones, it was in the past treated as a full-fledged geologic period between the Devonian and the Pennsylvanian.

The Neogene is a geologic period and system in the International Commission on Stratigraphy ( ICS ) Geologic Timescale starting 23. 03 ± 0. 05 million years ago and ending 2. 588 million years ago.

The Ordovician () is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488. 3 ± 1. 7 to 443. 7 ± 1. 5 million years ago.

As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly uncertain.

In North America, where the early Carboniferous beds are primarily marine limestones, the Pennsylvanian was in the past treated as a full fledged geologic period between the Mississippian and the Permian.

The Permian is a geologic period and system which extends from 299. 0 ± 0. 8 to 251. 0 ± 0. 4 Ma ( Million years ago ).

The Paleogene ( alternatively British English Palaeogene or Palæogene, informally Lower Tertiary ) is a geologic period and system that began 65. 5 ± 0. 3 and ended 23. 03 ± 0. 05 million years ago and comprises the first part of the Cenozoic Era.

*** Ediacaran: The youngest geologic period within the Neoproterozoic Era.

The Spindletop dome was derived from the Louann Salt evaporite layer of the Jurassic geologic period.

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443. 7 ± 1. 5 million years ago ( mya ), to the beginning of the Devonian Period, about 416. 0 ± 2. 8 mya.

The Triassic is a geologic period and system that extends from about 250 to 200 Ma ( million years ago ).

Tertiary is an officially deprecated but still widely used term for a geologic period from 65 million to 2. 6 million years ago, a time span that lies between the superseded Secondary period and the Quaternary.

Young sedimentary rocks, especially those of Quaternary age ( the most recent period of the geologic time scale ) are often still unconsolidated.

This class of arthropod is thought to be among the first animals to have colonised land during the Silurian geologic period.

It is the longest of the Phanerozoic eras, and is subdivided into six geologic periods ( from oldest to youngest ): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

Gypsum has been dated to almost every geologic age since the Silurian Period 443. 7 ± 1. 5 Ma.

Deposition resumed in the Cambrian period and continued through the Paleozoic era, creating nine major formations which together are 4, 000 feet ( 1, 200 m ) thick ( the only geologic period in the Paleozoic not represented is the Silurian ).

* Ludlow epoch, part of the Silurian period in the geologic time scale

Category: Silurian geologic formations

The Paleocene recovery of plants began with recolonizations by fern species, represented as a fern spike in the geologic record ; this same type of fern recolonization was observed after the 1980 Mount St. Helens eruption .< ref name =" SchultzDhondt ">

Lyell's interpretation of geologic change as the steady accumulation of minute changes over enormously long spans of time was a powerful influence on the young Charles Darwin.

This was in contrast to catastrophism, a geologic idea of abrupt changes, which had been adapted in England to support belief in Noah's flood.

The geologic time scale was developed based on the relative ages of rock strata as determined by the early paleontologists and stratigraphers.

The term was used more broadly in older geologic literature.

Completed in 1815, it was the first national-scale geologic map, and by far the most accurate of its time.

A large advance in geology in the advent of the 20th century was the ability to give precise absolute dates to geologic events through radioactive isotopes and other methods.

An estimate of of dense-rock equivalent pyroclastic material, known the Youngest Toba tuff, was blasted from the youngest caldera during one of the largest single explosive volcanic eruptions in geologic history.

The Permian – Triassic ( P – Tr ) extinction event, informally known as the Great Dying, was an extinction event that occurred 252. 28 Ma ( million years ) ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras.

Because fossils identifiable as P. sternbergi are found exclusively in the lower layers of the Niobrara Formation, and P. longiceps fossils exclusively in the upper layers, a fossil lacking the skull can be identified based on its position in the geologic column ( though for many early fossil finds, precise data about its location was not recorded, rendering many fossils unidentifiable ).

The most recent work in the Gulf of Khambhat took place from October 2003 to January 2004 and was primarily a geologic study.

Just north of the Crystal Springs reservoir is San Andreas Lake after which the famous geologic fault was named.

Uniformitarianism was originally proposed in contrast to catastrophism, which states that the distant past " consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility " Especially in the late 19th and early 20th centuries, most geologists took this interpretation to mean that catastrophic events are not important in geologic time ; one example of this is the debate of the formation of the Channeled Scablands due to the catastrophic Missoula glacial outburst floods.

An important result of this debate and others was the re-clarification that, while the same principles operate in geologic time, catastrophic events that are infrequent on human time-scales can have important consequences in geologic history.

Before the development of geologic concepts during the 19th century, the presence of mountains was explained in Christian contexts as a result of the Biblical Deluge.

The eastern part of the Glarus Alps contains a major thrust fault which was declared a geologic UNESCO world heritage site ( the Swiss Tectonic Arena Sardona ).

Over geologic history, it was eroded by Pumpkin Creek and other watercourses, and much of the county now lies below the original High Plains level.

In 1955 oil was discovered in this geologic structure at a greater depth than had previously been considered as feasible, and so the Citronelle Dome was among the first of many " deep " oil fields.

In 2009 the The Van Horn Advocate announced that the Long Now Foundation was starting geologic testing for an underground space to house a 10, 000 Year Clock of the Long Now, on the Bezos ranch, north of Van Horn.

) A potable water supply was found in a geologic unit only distant, and pipes were built to transport it to town in 1929.