The atmosphere becomes much more oxygenic while more cyanobacterial stromatolites appear. Vredefort and Sudbury Basin asteroid impacts. Much orogeny. Penokean and Trans-Hudsonian Orogenies in North America. Early Ruker Orogeny in Antarctica, 2,000–1,700Ma. Glenburgh Orogeny, Glenburgh Terrane, Australian continent c. 2,005–1,920Ma. Kimban Orogeny, Gawler craton in Australian continent begins.

Bassett, Michael G. (1 June 1979). "100 Years of Ordovician Geology". Episodes. 2 (2): 18–21. doi: 10.18814/epiiugs/1979/v2i2/003. ISSN 0705-3797. Borolanite– Variety of nepheline syenite from Loch Borralan, Scotland – A variety of nepheline syenite from Loch Borralan, Scotland Tanaka, Kenneth L. (1986). "The stratigraphy of Mars". Journal of Geophysical Research. 91 (B13): E139. Bibcode: 1986JGR....91E.139T. doi: 10.1029/JB091iB13p0E139. ISSN 0148-0227. Middle Miocene climate optimum temporarily provides a warm climate. [81] Extinctions in middle Miocene disruption, decreasing shark diversity. First hippos. Ancestor of great apes. Steno, Nicolaus (1669). Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... (in Latin). W. Junk.

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Relationships of unconformities – Geologic features representing periods of erosion or non-deposition, indicating non-continuous sediment deposition. Berman, R.G., 1991, Thermobarometry using multi-equilibrium calculations; a new technique, with petrological applications, The Canadian Mineralogist, v. 29 (4), p. 833–855

a b c d Royer, Dana L. (2006). "CO 2-forced climate thresholds during the Phanerozoic" (PDF). Geochimica et Cosmochimica Acta. 70 (23): 5665–75. Bibcode: 2006GeCoA..70.5665R. doi: 10.1016/j.gca.2005.11.031. Archived from the original (PDF) on 27 September 2019 . Retrieved 6 August 2015. Montenari, Michael (2020). Carbon Isotope Stratigraphy (1sted.). Amsterdam: Academic Press (Elsevier). ISBN 978-0-12-820991-2. On the BGS Geological Timechart, epoch boundaries (era boundaries in the Precambrian) have been assigned radiometric ages taken from the component timescales. Neither the dates nor even the boundaries themselves are fixed, however. Improved radiometric dating of strata is continually taking place and sometimes leads to improved age assignments for individual chronostratigraphical boundaries. Eventually, these piecemeal changes are incorporated into a revision of a complete geological timescale, such as used in this chart. 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. Chaotian Era/Erathem (4567–4404 Ma) – the name alluding both to the mythological Chaos and the chaotic phase of planet formation. [57] [70] [71]

Holmes, A. (1 January 1959). "A revised geological time-scale". Transactions of the Edinburgh Geological Society. 17 (3): 183–216. doi: 10.1144/transed.17.3.183. ISSN 0371-6260. S2CID 129166282. How does the horizontal geothermal gradient compare with vertical geothermal gradients in stable continental crust?

Kleisian or Syndian ( 1000–800 Ma) – respectively from the Greek words κλείσιμο ( kleísimo) meaning 'closure', and σύνδεση ( sýndesi) meaning 'connection'. Kyanite is one of the weirder minerals out there. Its defining feature is that the hardness of the mineral varies depending on the angle you approach it compared to the angle of the crystal’s growth. It’s usually known as large, bladed crystals but it can also be found as small individual crystals of deep blue color. These latter crystals are columnar.

References

A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundaries of stages on the geologic time scale. [9] (Recently this has been used to define the base of a system) [10] Bleeker, W. (17 March 2005), Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (eds.), "Toward a "natural" Precambrian time scale", A Geologic Time Scale 2004 (1ed.), Cambridge University Press, pp.141–146, doi: 10.1017/cbo9780511536045.011, ISBN 978-0-521-78673-7 , retrieved 9 April 2022 Bauer, Andrew M.; Edgeworth, Matthew; Edwards, Lucy E.; Ellis, Erle C.; Gibbard, Philip; Merritts, Dorothy J. (16 September 2021). "Anthropocene: event or epoch?". Nature. 597 (7876): 332. Bibcode: 2021Natur.597..332B. doi: 10.1038/d41586-021-02448-z. ISSN 0028-0836. PMID 34522014. S2CID 237515330. 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]

Vaalbaran Period/System ( 3490–3020 Ma) – based on the names of the Kapvaal (Southern Africa) and Pilbara (Western Australia) cratons, to reflect the growth of stable continental nuclei or proto- cratonic kernels. [57] As tiny skeletal fragments from coral, shellfish, and plankton accumulate on ocean floors, they fuse over time into solid limestone. Chalk varieties stem from particularly fine-grained planktonic remains, while fossil-rich limestone often forms in shallow reef environments. Pyroxenite belongs to the ultramafic group, meaning that it consists almost entirely of dark minerals rich in iron and magnesium. Specifically, its silicate minerals are mostly pyroxenes rather than other mafic minerals such as olivine and amphibole. In the field, pyroxene crystals display a stubby shape and square cross-section while amphiboles have a lozenge-shaped cross-section. Niels Stensen, more commonly known as Nicolas Steno (1638–1686), is credited with establishing four of the guiding principles of stratigraphy. [29] In De solido intra solidum naturaliter contento dissertationis prodromus Steno states: [34] [35] 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.

Rocks: Igneous, Metamorphic and Sedimentary

Carr, Michael H.; Head, James W. (1 June 2010). "Geologic history of Mars". Earth and Planetary Science Letters. Mars Express after 6 Years in Orbit: Mars Geology from Three-Dimensional Mapping by the High Resolution Stereo Camera (HRSC) Experiment. 294 (3): 185–203. Bibcode: 2010E&PSL.294..185C. doi: 10.1016/j.epsl.2009.06.042. ISSN 0012-821X. a b c d e f g h i j k l m F. M. Gradstein (2012). The geologic time scale 2012. Volume 2 (1sted.). Amsterdam: Elsevier. ISBN 978-0-444-59448-8. OCLC 808340848. Derived from the Greek words παλιός ( palaiós) meaning 'old', and γενεά ( geneá) meaning 'genesis' or 'birth'. W. B. Harland (1990). A geologic time scale 1989. Cambridge: Cambridge University Press. ISBN 0-521-38361-7. OCLC 20930970. Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. The Henry Mountains of Utah are a famous topographic landform formed by this process. Laccoliths bulge upwards; a similar downward-bulging intrusion is called a lopolith.