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NOTE:  Data obtained from Internet sources and checked with

various authors for relative accuracy as of 2020


CLICK All To Enlarge




       DATE APROXIMATIONS                                                                                 DISCUSSION            REFERENCES


80,000 B.C. ---------

80-40,000 B.C. ---- 

40,000 B.C. ---------

39,000 B.C. -------- 

28,000 B.C. ---------

16,000 B.C. ---------
13,000 B.C. ---------

12,000 B.C. ---------

10,000 B.C. ---------

 9,000 B.C. ---------                                  

8,000 B.C. --------- 

 6,000 B.C. -----------

5,500 - 6,000 B.C.--

6,000-3,500 B.C.----

4,000 B.C. -----------

1,700 B.C. ----------- 

1,420  B.C. -----------

1,290 –1,180 B.C. --

1,100 B.C. --------  

    597 A.D. ---------- 

600-700 A.D. -----

    635 A.D. ----------

c 950-1250 A.D. ----

c 1360-1860 A.D. ---- 1870 – 2020 ---


Modern humans appear in southern Africa (judged from jewelry production)

Several catastrophic climatic changes decimate human population

Small group of modern humans cross Red Sea to Yemen

Artistic cave paintings appear at diverse locations

Small carvings of human females appear from Europe through Asia

The climate begins to warm
Advance of glaciers stops, and sea levels begin to rise

Flooding over vast areas of the earth intensifies

Development of reliable ocean navigation opened up the world around

Mini Ice Age lasts a few hundred years.  Seafarers from Morocco and northern

Spain explore entire west coast of Europe.  Caucasian race appears in Libya

Ice Age mega fauna goes extinct.  Societies become more centrally directed.

Specialized trades expand, longevity increases.  Ireland to Scandinavia colonized.
Bering Strait land bridge drowned, halting migration of humans and animals

Language becomes more organized and developed (See Linguistics)

Migrations out of North Africa to points east and north (as desert expands)

The Holocene Maximum warm period

Peteroborough, Canada petroglyphs carved (See Bronze Age)

Isle of Thera volcano erupts, devastating Crete & other areas

Major attacks by Sea Peoples on Egypt (attempt to reestablish Goddess religion)

Hebrews leave Egypt

Benedictine clerics expand Christian conversion activity in Europe

Horsecreek Petroglyph carved in West Virginia ? (See Horsecreek)

Roman Catholic sponsored Invention of modern European languages expanded

Medieval Warm Period

Little Ice Age

Industrial Age , Global Warming






          The Earth has been ice-free (even at the poles) for most of its history.  However, these iceless periods have been interrupted by several major glaciations (called Glacial Epochs) and we are in one now in the 21st Century.   Each glacial epoch consists of many advances and retreats of ice fields.  These ice fields tend to wax and wane in about 100,000, 41,000 and 21,000 year cycles.  Each advance of ice has been referred to as an "Ice Age" but it is important to realize that these multiple events are just variations of the same glacial epoch.  The retreat of ice during a glacial epoch is called an Inter-Glacial Period and this is our present climate system.


          The existing Plio-Pleistocene Glacial Epoch began about 3.2 million years ago and is probably linked to the tectonic construction of the Isthmus of Panama which prevented the circulation of Atlantic and Pacific waters and eventually triggered a slow sequence of events that finally led to cooling of the atmosphere and the formation of new ice fields by about 2.5 million years ago.


          Thus far, the Earth has had around 15 to 20 individual major advances and subsequent retreats of the ice field in our current Glacial Epoch.  The last major advance of glacial ice peaked about 18,000 years ago and since that time the ice has generally been retreating although with some short-term interruptions (See Graph above).  What we are presently experiencing in Greenland and other continents is a rapid melting of surrounding sea ice by rising ocean temperatures and a widening of the Gulf Stream.  Greenland's continental glaciers are also retreating due to an accumulation of atmospheric soot and a reduction of fresh snow to cover it.  Oceanic islands are vulnerable to inundation by subsequent rising ocean levels and destruction of protective coral reefs as a consequence of higher  ocean temperatures.



Abramov, O. & Mojzsis, S. J. Microbial habitability of the Hadean Earth during the late heavy bombardment. Nature 459, 419–422 (2009).

Allwood, A. C. et al. Stromatolite reef from the early Archean era of Australia. Nature 441, 714–718 (2006).

Anbar, A. D. et al. A whiff of oxygen before the Great Oxidation Event? Science 317, 1903–1906 (2007).

Beerling, D. et al. Methane and the CH4-related greenhouse effect over the past 400 million years. American Journal of Science 309, 97–113 (2009).

Bekker, A. & Kaufman, A. J. Oxidative forcing of global climate change; A biogeochemical record across the oldest Paleoproterozoic ice age in North America. Earth and Planetary Science Letters 258, 486–499 (2007).

Bekker, A. et al. Dating the rise of atmospheric oxygen. Nature 427, 117–120 (2004).

Berner, R. A. GEOCARBSULF: A combined model for Phanerozoic atmospheric O2 and CO2. Geochimica et Cosmochimica Acta 70, 5653–5664 (2006).

Berner, R. A. Phanerozoic atmospheric oxygen: New results using the GEOCARBSULF model. American Journal of Science 309, 603–606 (2009).

Blake, R. E., Chang, S. J. & Lepland, A. Phosphate oxygen isotope evidence for a temperate and biologically active Archean ocean. Nature 464, 1029–1033.

Brocks, J. J. et al. Archean molecular fossils and the early rise of Eukaryotes. Science 285, 1033–1036 (1999).

Byerly, G. R. et al. An Archean impact layer from the Pilbara and Kaapvaal cratons. Science 297, 1325–1327 (2002).

Canfield, D. E. & Teske, A. Late Proterozoic rise in atmospheric oxygen concentration inferred from phylogenetic and sulphur-isotope studies. Nature 382, 127–132 (1996).

Canfield, D. E., Poulton, S. W. & Narbonne, G. M. Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life. Science 315, 92–95 (2006).

Catling, D. C., Zahnle, K. J. & McKay, C. P. Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth. Science 293, 839–843 (2001).

Clayton, R. N., O’Neil, J. R. & Mayeda, T. K. Oxygen isotope exchange between quartz and water. Journal of Geophysical Research 77, 3057–3067 (1972).

Des Marais, D. J. et al. Carbon isotope evidence for the stepwise oxidation of the Proterozoic environment. Nature 359, 605–609 (1992).

Eugster, H. P. Sodium carbonate-bicarbonate minerals as indicators of PCO2. Journal of Geophysical Research 71, 3369–3378 (1966).

Evans, D. A. A fundamental Precambrian–Phanerozoic shift in Earth’s glacial style? Tectonophysics 375, 353–385 (2003).

Evans, D. A., Beukes, N. J. & Kirschvink, J. L. Low-latitude glaciations in the Paleoproterozoic era. Nature 386, 262–266 (1997).

Farquhar, J., Bao, H. & Thiemans, M. Atmospheric influences of Earth’s earliest sulfur cycle. Science 289, 756–758 (2000).

Goldblatt, C. & Zahnle, K. J. Clouds and the faint young Sun paradox. Climate of the Past 7, 203–220 (2011).

Goldblatt, C., Lenton, T. M. & Watson, A. J. Bistability of atmospheric oxygen and the Great Oxidation. Nature 443, 683–686 (2006).

Gough, D. O. Solar interior structure and luminosity variations. Solar Physics 74, 21–34 (1981).

Haqq-Misra, J. D. et al. Revised, hazy methane greenhouse for the Archean Earth. Astrobiology 8, 1127–1137 (2008).

Hessler, A. M. & Lowe, D. R. Weathering and sediment generation in the Archean: An integrated study of the evolution of siliciclastic sedimentary rocks of the 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa. Precambrian Research 151, 185–210 (2006).

Hessler, A. M. et al. A lower limit for atmospheric carbon dioxide levels 3.2 billion years ago. Nature 428, 736–738 (2004).

Heubeck, C. An early ecosystem of Archean tidal microbial mats (Moodies Group, South Africa, ca. 3.2 Ga). Geology 37, 931–934 (2009).

Hofmann, H. J. Precambrian microflora, Belcher Islands, Canada: Significance and systematics. Journal of Paleontology 50, 1040–1073 (1976).

Hofmann, H. J. et al. Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia. Geological Society of America Bulletin 111, 1256–1262 (1999).

Holland, H. D. The oxygenation of the atmosphere and oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361, 903–915 (2006).

Hren, M. T., Tice, M. M. & Chamberlain, C. P. Oxygen and hydrogen isotope evidence for a temperate climate 3.42 billion years ago. Nature 205, 205–208 (2009).

Jaffres, J. B. D., Shields, G. A. & Wallmann, K. The oxygen isotope evolution of sea water; A critical review of a long standing controversy and an improved geological water cycle model for the past 3.4 billion years. Earth-Science Reviews 83, 83–122 (2007).

Kashefi, K. & Lovley, D. R. Extending the upper temperature limit for life. Science 301, 934 (2003).

Kasting, J. F. Theoretical constraints on oxygen and carbon dioxide concentrations in the Precambrian atmosphere. Precambrian Research 34, 205–229 (1987).

Kasting, J. F. Earth’s early atmosphere. Science 259, 920–926 (1993).

Kasting, J. F., Liu, S. C. & Donahue, T. M. Oxygen levels in the prebiological atmosphere. Journal of Geophysical Research 84, 3097–3107 (1979).

Kasting, J. F. et al. Paleoclimates, ocean depth, and the oxygen isotopic composition of seawater. Earth and Planetary Science Letters 252, 82–93 (2006).

Kharecha, P., Kasting, J. & Seifert, J. A. A coupled atmosphere-ecosystem model of the early Archean Earth. Geobiology 3, 53–76 (2005).

Knauth, L. P. & Lowe, D. R. High Archean climatic temperatures inferred from oxygen isotope geochemistry of cherts in the 3.5 Ga Swaziland Supergroup, South Africa. Geological Society of America Bulletin 155, 566–580 (2003).

Knoll, A. H. The early evolution of eukaryotic organisms: A geological perspective. Science 256, 922–627 (1992).

Knoll, A. H. et al. Eukaryotic organisms in Proterozoic oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361, 1023–1038 (2006).

Kopp, R. E. et al. The Paleoproterozoic snowball Earth: A climatic disaster triggered by the evolution of oxygenic photosynthesis. Proceedings of the National Academy of Sciences of the United States of America 102, 11131–11136 (2005).

Kreidenweis, S. M. & Seinfeld, J. H. Nucleation of sulfuric acid-water and methanesulfonic acid-water solution particles: Implications for the atmospheric chemistry of organosulfur species. Atmosphere Environment 22, 283–296 (1988).

Lin, L-H. et al. Long-term sustainability of a high-energy, low-diversity crustal biome. Science 314, 479–482 (2006).

Locklair, R. E. & Lerman, A. A model of Phanerozoic cycles of carbon and calcium in the global ocean: Evaluation and constraints on ocean chemistry and input fluxes. Chemical Geology 217, 113–126 (2005).

Lowe, D. R. Restricted shallow water sedimentation of Early Archean stromatolitic and evaporitic strata of the Strelley Pool Chert, Pilbara Block, Western Australia. Precambrian Research 19, 239–283 (1983).

Lowe, D. R. & Tice, M. M. Geologic evidence for Archean atmosphere and climatic evolution: Fluctuating levels of CO2, CH4, and O2 with an overriding tectonic control. Geology 32, 493–496 (2004).

Mather, T. A., Pyle, D. M. & Allen, A. G. Volcanic source for fixed nitrogen in the early Earth’s atmosphere. Geology 32, 905–908 (2004).

Maas, R. et al. The Earth’s oldest known crust: A geochronological and geochemical study of 3900–4200 Ma detrital zircons from Mt. Narryer and Jack Hills, Western Australia. Geochimica et Cosmochimica Acta 56, 1281–1300 (1992).

Marmo, J. S. & Ojakangas, R. W. Lower Proterozoic glaciogenic deposits, eastern Finland. Geological Society of America Bulletin 98, 1055–1062 (1984).

Melezhik, V. A. Multiple causes of Earth’s earliest global glaciations. Terra Nova 18, 130–137 (2006).

Mojzsis, S. J., Harrison, T. M. & Pidgeon, R. T. Oxygen-isotope evidence from ancient zircons for liquid water at the Earth’s surface 4,300 Myr ago. Nature 409, 178–181 (2001).

Narbonne, G. M. & Gehling, J. G. Life after snowball: The oldest complex Ediacaran fossils. Geology 31, 27–30 (2003).

Noffke, N. et al. A new window into Early Archean life: Microbial mats in Earth’s oldest siliciclastic tidal deposits (3.2 Ga Moodies Group, South Africa). Geology 34, 253–256 (2006).

Pavlov, A. A. & Kasting, J. F. Mass-independent fractionation of sulfur isotopes in Archean sediments: Strong evidence for an anoxic Archean atmosphere. Astrobiology 2, 27–41 (2002).

Pavlov, A. A. et al. Greenhouse warming by CH4 in the atmosphere of early Earth. Journal of Geophysical Research 105, 11981–11990 (2000).

Pavlov, A. A. et al. Methane-rich Proterozoic atmosphere? Geology 31, 87–90 (2003).

Peck, W. H. et al. Oxygen isotope ratios and rare earth elements in 3.3 to 4.4 Ga zircons: Ion microprobe evidence for high delta O-18 continental crust and oceans in the Early Archean. Geochimica et Cosmochimica Acta 65, 4215–4229 (2001).

Rashby, S. E. et al. Biosynthesis of 2-methylbacteriohopanepolyols by an anoxygenic phototroph. Proceedings of the National Academy of Sciences of the United States of America 104, 15099–15014 (2007).

Rasmussen, B. & Buick, R. Redox state of the Archean atmosphere: Evidence from detrital heavy minerals in ca. 3250–2750 Ma sandstones from the Pilbara Craton, Australia. Geology 27, 115–118 (1999).

Rasmussen, B. et al. Reassessing the first appearance of eukaryotes and cyanobacteria. Nature 455, 1101–1105 (2008).

Rondanelli, R. & Lindzen, R. S. Can thin cirrus clouds in the tropics provide a solution to the faint young Sun paradox? Journal of Geophysical Research 115, 689–690 (2010).

Rosing, M. T. 13C-depleted carbon microparticles in >3700-Ma sea-floor sedimentary rocks from west Greenland. Science 283, 674–676 (1999).

Rosing, M. T. et al. No climate paradox under the faint Sun. Nature 464, 744–747 (2010).

Rossow, W. B., Henderson-Sellers, A. & Weinreich, S. K. Cloud feedback: A stabilizing effect for the early Earth? Science 217, 1247–1247 (1982).

Sagan, C. & Mullen, G. Earth and Mars – Evolution of atmospheres and surface temperatures. Science 177, 52–56 (1972).

Sheldon, N. D. Precambrian paleosols and atmospheric CO2 levels. Precambrian Research 147, 148–155 (2006).

Sleep, N. H. & Hessler, A. M. Weathering of quartz as an Archean climatic indicator. Earth and Planetary Science Letters 241, 594–602 (2006).

Summons, R. E. et al. 2-methyl-hopanoids as biomarkers for cyanobacterial oxygenic photosynthesis. Nature 400, 554–557 (1999).

Tice, M. M. & Lowe, D. R. Hydrogen-based carbon fixation in the earliest known photosynthetic organisms. Geology 34, 37–40 (2006).

Trainer, M. G. et al. Organic haze on Titan and the early Earth. Proceedings of the National Academy of Sciences of the United States of America 103, 18035–18042 (2006).

Valley, J. W. et al. A cool early Earth. Geology 30, 351–354 (2002).

Wilde, S. A. et al. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nature 409, 175–178 (2001).

Zachos, J. et al. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292, 686–693 (2001).

Zahnle, K. J. Photochemistry of methane and formation of hydrocyanic acid (HCN) in the Earth’s early atmosphere. Journal of Geophysical Research 91, 2819–2834 (1986).