User:Pixatplay/Books/DEEP TIME

Category:Paleontology Category:Dinosaurs Category:Prehistoric life Category:Fossils Category:Paleogeography Category:Geology Category:Geologic time scales Category:geology templates Category:Historical geology



= WELCOME TO DEEP TIME =

What is Deep Time?
Deep time is the concept of geologic time. The modern philosophical concept was developed in the 18th century by Scottish geologist James Hutton (1726–1797). Modern scientists believe, after a long and complex history of developments, that the age of the Earth is around 4.55 billion years.

Scientific concept of Deep Time
Hutton based his view of deep time on a form of geochemistry that had been developed in Scotland and Scandinavia from the 1750s onward. As mathematician John Playfair, one of Hutton's friends and colleagues in the Scottish Enlightenment, later remarked upon seeing the strata of the angular unconformity at Siccar Point with Hutton and James Hall in June 1788, "the mind seemed to grow giddy by looking so far into the abyss of time".

Early geologists such as Nicolas Steno and Horace-Bénédict de Saussure developed ideas of geological strata forming from water through chemical processes, which Abraham Gottlob Werner (1749–1817) developed into a theory known as Neptunism, envisaging the slow crystallisation of minerals in the ancient oceans of the Earth to form rock. Hutton's innovative 1785 theory, based on Plutonism, visualised an endless cyclical process of rocks forming under the sea, being uplifted and tilted, then eroded to form new strata under the sea. In 1788 the sight of Hutton's Unconformity at Siccar Point convinced Playfair and Hall of this extremely slow cycle, and in that same year Hutton memorably wrote "we find no vestige of a beginning, no prospect of an end".

Other scientists such as Georges Cuvier put forward ideas of past ages, and geologists such as Adam Sedgwick incorporated Werner's ideas into concepts of catastrophism; Sedgwick inspired his university student Charles Darwin to exclaim "What a capital hand is Sedgewick for drawing large cheques upon the Bank of Time!". In a competing theory, Charles Lyell in his Principles of Geology (1830–1833) developed Hutton's comprehension of endless deep time as a crucial scientific concept into uniformitarianism. As a young naturalist and geological theorist, Darwin studied the successive volumes of Lyell's book exhaustively during the Beagle survey voyage in the 1830s, before beginning to theorise about evolution.

Physicist Gregory Benford addresses the concept in Deep Time: How Humanity Communicates Across Millennia (1999), as does paleontologist and Nature editor Henry Gee in In Search of Deep Time: Beyond the Fossil Record to a New History of Life (2001)  Stephen Jay Gould's Time's Arrow, Time's Cycle (1987) also deals in large part with the evolution of the concept.

John McPhee discussed "deep time" at length with the layman in mind in Basin and Range (1981), parts of which originally appeared in the The New Yorker magazine. In Time's Arrow, Time's Cycle, Gould cited one of the metaphors McPhee used in explaining the concept of deep time: "Consider the Earth's history as the old measure of the English yard, the distance from the King's nose to the tip of his outstretched hand. One stroke of a nail file on his middle finger erases human history."

Concepts similar to geologic time were recognized in the 11th century by the Persian geologist and polymath Avicenna (Ibn Sina, 973–1037), and by the Chinese naturalist and polymath Shen Kuo (1031–1095).

The Roman Catholic theologian Thomas Berry (1914–2009) explored the spiritual implications of the concept of Deep Time. Berry proposes that a deep understanding of the history and functioning of the evolving universe is a necessary inspiration and guide for our own effective functioning as individuals and as a species. This view has greatly influenced the development of deep ecology and ecophilosophy. The experiential nature of the experience of deep time has also greatly influenced the work of Joanna Macy and John Seed.

H.G. Wells and Julian Huxley regarded the difficulties of coping with the concept of deep time as exaggerated:

"The use of different scales is simply a matter of practice", they said in The Science of Life (1929). "We very soon get used to maps, though they are constructed on scales down to a hundred-millionth of natural size. . . to grasp geological time all that is needed is to stick tight to some magnitude which shall be the unit on the new and magnified scale—a million years is probably the most convenient—to grasp its meaning once and for all by an effort of imagination, and then to think of all passage of geological time in terms of this unit."

= Geologic Time =

Geochronology and stratigraphy

 * Geologic time scale
 * Stratigraphy
 * International Commission on Stratigraphy
 * Period (geology)

Geologic time scale
(The Precambrian supereon accounts for 88% of all geologic time.)

The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. As with the time scales above, this time scale is based on the International Commission on Stratigraphy. (See lunar geologic timescale for a discussion of the geologic subdivisions of Earth's moon.) This table is arranged with the most recent geologic periods at the top, and the most ancient at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time.

The content of the table is based on the current official geologic time scale of the International Commission on Stratigraphy, with the epoch names altered to the early/late format from lower/upper as recommended by the ICS when dealing with chronostratigraphy.

Condensed graphical timelines
The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this compresses the most recent eon. Therefore, the second scale shows the most recent eon with an expanded scale. The second scale compresses the most recent era, so the most recent era is expanded in the third scale. Since the Quaternary is a very short period with short epochs, it is further expanded in the fourth scale. The second, third, and fourth timelines are therefore each subsections of their preceding timeline as indicated by asterisks. The Holocene (the latest epoch) is too small to be shown clearly on the third timeline on the right, another reason for expanding the fourth scale. The Pleistocene (P) epoch. Q stands for the Quaternary period.

Millions of Years

= Recommended viewing and reading =

Television Series

 * PBS Nova, |Life's Rocky Start.


 * BBC, |Journeys from the Centre of the Earth, presented by Professor Iain Stewart, 6 Parts.


 * BBC, Rise of the Continents, presented by Professor Iain Stewart, 4 episodes:
 * 1) Africa
 * 2) Australia
 * 3) The Americas
 * 4) Eurasia


 * BBC, Men of Rock, a 2010 TV series about pioneering geologists working in Scotland. It consists of three episodes presented by Professor Iain Stewart:
 * 1) Deep Time. The story of James Hutton, the founding father of geology.
 * 2) Moving Mountains. An examination of how geologist Edward Bailey discovered Scotland once had super volcanoes.
 * 3) The Big Freeze. The story of Louis Agassiz, who first proposed that the earth had experienced an ice age.


 * PBS Nova, Making North America (2015), the epic 3 billion-year story of how our continent came to be. From the palm trees that once flourished in Alaska to titanic eruptions that nearly tore the Midwest in two, discover how forces of almost unimaginable power gave birth to North America.
 * 1) Part 1: Origins.
 * 2) Part 2: Life
 * 3) Part 3: Humans


 * Channel4, UK, Catastrophe - This spectacular five-part documentary series, presented by Tony Robinson, investigates the history of natural disasters from the planet's beginnings to the present, putting a new perspective on our existence and suggesting that we are the product of catastrophe.
 * 1) Episode 1 - Birth of the Planet.
 * 2) Episode 2 - Snowball Earth.
 * 3) Episode 3 - Planet of Fire.
 * 4) Episode 4 - Asteroid Impact.
 * 5) Episode 5 - Survival Earth.

Related Links

 * Planet Theia