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

The Eocene ( symbol E < sub > O </ sub >) epoch, lasting from about 56 to 34 million years ago ( to ), is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.

In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition.

Before 630 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as " Global Standard Stratigraphic Ages ".

The Mississippian is a subperiod in the geologic timescale or a subsystem of the geologic record.

In the official geologic timescale, the Mississippian is subdivided into three stages:

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods ( or upper of two subsystems ) of the Carboniferous Period.

The current internationally used geologic timescale of the ICS gives the Mississippian and Pennsylvanian the rank of subperiods, subdivisions of the Carboniferous Period.

The Phanerozoic ( British English Phanærozoic ) is the current geologic eon in the geologic timescale, and the one during which abundant animal life has existed.

* Lunar geologic timescale

However, the Lunar geologic timescale embraces several major divisions relating to the Hadean and so these are sometimes used in a somewhat informal sense to refer to the same periods of time on Earth.

The mountain range gives its name to the French department of Jura, the Swiss Canton of Jura, and the Jurassic period of the geologic timescale.

Its age corresponds to the Rhaetian to lower Sinemurian stages of the geologic timescale, thus fully including the Hettangian stage.

* 1841 — The first global geologic timescale is defined by John Phillips based on the type of fossils found in different rock layers.

The Copernican Period in the lunar geologic timescale runs from approximately 1. 1 billion years ago to the present day.

The Eratosthenian period in the lunar geologic timescale runs from 3, 200 million years ago to 1, 100 million years ago.

The Nectarian Period of the lunar geologic timescale runs from 3920 million years ago to 3850 million years ago.

The Pre-Nectarian Period of the lunar geologic timescale runs from 4533 million years ago ( the time of the initial formation of the Moon ) to 3920 million years ago, when the Nectaris Basin was formed by a large impact.

In the Lunar geologic timescale, the Late Imbrian epoch occurred between 3800 million years ago to about 3200 million years ago.

In the lunar geologic timescale, the Early Imbrian epoch occurred between 3850 million years ago to about 3800 million years ago.

The Iapetus Ocean was an ocean that existed in the Neoproterozoic and Paleozoic eras of the geologic timescale ( between 600 and 400 million years ago ).

The Barremian is an age in the geologic timescale ( or a chronostratigraphic stage ) between 130. 0 ± 1. 5 Ma ( million years ago ) and 125. 0 ± 1. 0 Ma ).

The Late Cretaceous ( 100. 5 – 66 Ma ) is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale.

No large earthquake has occurred on the Hayward Fault near Berkeley in historic times ( except possibly in 1836 ), but seismologists warn about the geologic record of large temblors several times in the deeper past, and their current assessment is that a quake of 6. 5 or greater is imminent, sometime within the next 30 years.

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.

The end of the Cretaceous is defined by the K – Pg boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic Eras.

This process occurs slowly in nature and is responsible for the deposition and accumulation of limestone over geologic time.

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.

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 next-larger division of geologic time is the eon.

The recession of the glaciers is so recent ( in geologic terms ) that modern-day drainage patterns are immature and poorly established.

The majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth.

Engineering geology is the application of the geologic principles to engineering practice for the purpose of assuring that the geologic factors affecting the location, design, construction, operation and maintenance of engineering works are properly addressed.

A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for a particular boundary on the geologic time scale.

Once a GSSP boundary has been agreed upon, a " golden spike " is driven into the geologic section to mark the precise boundary for future geologists ( though in practice the " spike " need neither be golden nor an actual spike ).

The geologic time scale is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history.

Granite has been intruded into the crust of the Earth during all geologic periods, although much of it is of Precambrian age.

In hydrology the harmonic mean is used to average hydraulic conductivity values for flow that is perpendicular to layers ( e. g. geologic or soil ) while flow parallel to layers uses the arithmetic mean.

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.

** Neoproterozoic: The youngest geologic era of the Proterozoic Eon, from the Cambrian Period lower boundary ( 542 Ma ) back to 1000 Ma.

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 ).

In mantle plume theory, this is explained by plumes tapping a deep, primordial reservoir in the lower mantle, where the original, high < sup > 3 </ sup > He /< sup > 4 </ sup > He ratios have been preserved throughout geologic time.

The area is still rebounding, however, and the rise could further rearrange drainage within geologic time by raising the outlet of Lake Ontario sufficient for it to drain at some other, lower point.

On a geologic map, anticlines are usually recognized by a sequence of rock layers that are progressively older toward the center of the fold because the uplifted core of the fold is preferentially eroded to a deeper stratigraphic level relative to the topographically lower flanks.

The base ( beginning ) of the Hirnantian stage is defined by the first appearance in the geologic record of the graptolite Normalograptus extraordinarius, and thus, the Normalograptus extraordinarius biozone defines the early ( or lower ) part of the Hirnantian.

These minerals often produce lower precision ages than igneous and metamorphic minerals traditionally used for age dating, but are more common in the geologic record.

The fossils were found in a layer of tuff, between a lower, older geologic layer dubbed Member I and a higher, newer layer dubbed Member III.