Editing Deep time (section)

== Origins and definition ==
The philosophical concept of geological time was developed in the 18th century by [[Scottish people|Scottish]] geologist [[James Hutton]];{{sfn|Palmer|Zen}}{{sfn|Kubicek|2008}} his "system of the habitable Earth" was a [[deism|deistic]] mechanism keeping the world eternally suitable for humans.<ref name="Rudwick68">{{cite book|author=M. J. S. Rudwick|title=Earth's Deep History: How It Was Discovered and Why It Matters|url=https://books.google.com/books?id=lYyRBAAAQBAJ&pg=PA68|date=15 October 2014|publisher=University of Chicago Press|isbn=978-0-226-20393-5|pages=68–70}}</ref> The modern concept entails huge changes over the [[age of the Earth]] which has been determined to be, after a long and complex history of developments, around 4.55 billion years.<ref>{{Cite news|url=http://www.scientificamerican.com/article/how-science-figured-out-the-age-of-the-earth/|title=How Science Figured Out the Age of Earth|last=Braterman|first=Paul S.|work=Scientific American|access-date=2016-04-17}}</ref>{{Life timeline}}
James Hutton based his view of deep time on a form of geochemistry that had developed in Scotland and Scandinavia from the 1750s onward.<ref>{{cite book |last = Eddy |first = Matthew Daniel |title = The Language of Mineralogy: John Walker, Chemistry and the Edinburgh Medical School 1750–1800 |date = 2008 |publisher = [[Ashgate Publishing]] |location = London |page = Ch. 5 |url = https://www.academia.edu/1112014}}</ref>  As mathematician [[John Playfair]], one of Hutton's friends and colleagues in the [[Scottish Enlightenment]], remarked upon seeing the [[stratum|strata]] of the [[Unconformity|angular unconformity]] at [[Siccar Point]] with Hutton and [[Sir James Hall, 4th Baronet|James Hall]] in June 1788, "the mind seemed to grow giddy by looking so far into the abyss of time".{{sfn|Playfair|1805}}<ref>{{cite book |last= McPhee |first= John |date= 1981 |title= Book 1: Basin and Range, in Annals of the Former World |location= New York |publisher= [[Farrar, Straus and Giroux]] |page= [https://archive.org/details/annalsofformerwo00mcph/page/79 79] |isbn= 0-374-10520-0 |author-link= John McPhee }}</ref>