The names of geologic time units are defined for chronostratigraphic units with the corresponding geochronologic unit sharing the same name with a change to the latter (e.g. Phanerozoic Eonothem becomes the Phanerozoic Eon). Names of erathems in the Phanerozoic were chosen to reflect major changes in the history of life on Earth: Paleozoic (old life), Mesozoic (middle life), and Cenozoic (new life). Names of systems are diverse in origin, with some indicating chronologic position (e.g., Paleogene), while others are named for lithology (e.g., Cretaceous), geography (e.g., Permian), or are tribal (e.g., Ordovician) in origin. Most currently recognised series and subseries are named for their position within a system/series (early/middle/late); however, the ICS advocates for all new series and subseries to be named for a geographic feature in the vicinity of its stratotype or type locality. The name of stages should also be derived from a geographic feature in the locality of its stratotype or type locality. [7] Butcher, Andy (26 May 2004). "Re: Ediacaran". LISTSERV 16.0 - AUSTRALIAN-LINGUISTICS-L Archives. Archived from the original on 23 October 2007 . Retrieved 19 July 2011. a b c Precambrian or pre-Cambrian is an informal geological term for time before the Cambrian period Dense masses of microscopic quartz crystals give chert its smooth, splintery fracture and notable durability. Nodules of chert often occur interbedded within limestone and dolostone strata, creating picturesque banded patterns. The red and brown hues common in some chert stem from iron oxide inclusions. Greater than 75% silt (1/256 to 1/16 mm) and clay (<1/256 mm), not bedded, well-sorted, grains too fine to judge roundness using hand lens

a b c d e f g h i Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes (updateded.). 36 (3): 199–204. doi: 10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. Greenland ice sheet develops [79] as the cold slowly intensifies towards the Pleistocene. Atmospheric O 2 and CO 2 content reaches present-day levels while landmasses also reach their current locations (e.g. the Isthmus of Panama joins the North and South Americas, while allowing a faunal interchange). The last non-marsupial metatherians go extinct. Australopithecus common in East Africa; Stone Age begins. [80]

newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\) Granite’s resilience and aesthetic qualities have made it a constructors’ favorite for millennia. Ancient civilizations from Egypt to China utilized the stone’s compressive strength and polishability in monuments and sculptures. Today, dimensioned granite slabs and tiles cover buildings, kitchens, and public spaces globally. Great Oxidation Event (due to cyanobacteria) increases oxygen. Sleaford Orogeny on Australian continent, Gawler Craton 2,440–2,420Ma.

Head, Martin J.; Steffen, Will; Fagerlind, David; Waters, Colin N.; Poirier, Clement; Syvitski, Jaia; Zalasiewicz, Jan A.; Barnosky, Anthony D.; Cearreta, Alejandro; Jeandel, Catherine; Leinfelder, Reinhold (15 November 2021). "The Great Acceleration is real and provides a quantitative basis for the proposed Anthropocene Series/Epoch". Episodes. 45 (4): 359–376. doi: 10.18814/epiiugs/2021/021031. ISSN 0705-3797. S2CID 244145710. Cox, Simon J. D. "SPARQL endpoint for CGI timescale service". Archived from the original on 6 August 2014 . Retrieved 3 August 2014. Humboldt, Alexander von (1799). Ueber die unterirdischen Gasarten und die Mittel ihren Nachtheil zu vermindern: ein Beytrag zur Physik der praktischen Bergbaukunde (in German). Vieweg. a b Lewis, Cherry L. E. (2001). "Arthur Holmes' vision of a geological timescale". Geological Society, London, Special Publications. 190 (1): 121–138. Bibcode: 2001GSLSP.190..121L. doi: 10.1144/GSL.SP.2001.190.01.10. ISSN 0305-8719. S2CID 128686640. Critical Thinking: Some geoscientists suggest using the term suture zone to describe where ophiolites occur during continent-continent convergence. Looking at the map, do you think this term is appropriate for the Himalayan Mountains. Explain your answer.

First uncontroversial living organisms: at first protocells with RNA-based genes around 4000 Ma, after which true cells ( prokaryotes) evolve along with proteins and DNA-based genes around 3800 Ma. The end of the Late Heavy Bombardment. Napier Orogeny in Antarctica, 4,000±200Ma. Ophiolites offer clues to where oceanic crust used to exist, and they help geologists understand processes at mid-ocean ridges. Minerals don’t always break in predictable ways, and that’s when we use the term fracture. Fracture describes irregular breakage in minerals, which usually occurs on mineral planes that don’t have any weak bonds. This sounds easy enough; flat surfaces mean cleavage, and uneven surfaces mean fracture, but the truth is that it can be messy. Minerals can appear to have flat surfaces that are not actually cleavage, and fracturing can occur along planes of cleavage. This is why you need to look closely at the surface of a mineral using a hand lens. The term luster describes how light interacts with the surface of a mineral. There are many different terms used to describe the luster of a mineral, but for this lab manual, we are only concerned with metallic and non-metallic lusters (does it look like a metal or does it not look like a metal, respectively; Figures 2.4a and 2.4b). Be careful, though, because shiny doesn’t always mean it’s metallic. The technical difference between metallic and non-metallic is that metallic minerals do not allow light to pass through the atomic structure, and non-metallic minerals do allow some light to pass through. Figure 2.4a – Pyrite, a mineral with a metallic luster. Image credit: Wikimedia Commons user JJ Harrison, CC BY-SA. Figure 2.4b – Quartz, a mineral with a non-metallic luster and six-sided crystal form. Image credit: Wikimedia Commons user Didier Descouens, CC BY-SA. Streak What is the geothermal gradient along the Tana River? To determine the horizontal geothermal gradient, determine the distance between the two points you used for estimating the metamorphic temperature.