We reconstruct Earth's ancient past using physical, chemical, and/or biological signatures preserved in rocks, called proxies. From such proxies, we are able to reconstruct ancient climate trends, like temperature, atmospheric composition, ocean chemistry, oxygen levels, carbon dioxide levels, mountain chain positions, elevations, plate tectonic events, volanic eruption events, earthquakes, wildfires, ocean anoxic events, impact events, glacial expansions and contractions, sea level rise and fall, etc. as well as biological events, like evolutionary and extinction events. In the many Earth history videos on my channel, I go over such events, but in this video, I go over what kind of proxies we use to reconstruct such ancient events and conditions! I know this video is long, so I broke it into sections, which cover physical proxies, chemical proxies, & biological proxies, respectively. I also included chapters listed below and on the timebar of the video for you to use if you'd like to skip to a specific section. Hope you enjoy! ;)
References:
Zachos et al., 2001- Trends, rhythms, and aberrations in global climate 65 Ma to present: doi.org/10.1126/science.1059412
McElwain & Punyasena, 2007- Mass extinction events and the plant fossil record: doi.org/10.1016/j.tree.2007.0...
Falkowski et al., 2005- The rise of oxygen over the past 205 million years and the evolution of large placental mammals: doi.org/10.1126/science.1116047
Hayes, 2001- Fractionation of the isotopes of carbon and hydrogen in biosynthetic processes. Reviews in mineralogy and geochemistry: doi.org/10.2138/gsrmg.43.1.225
Delano, 2001- Redox history of the Earth's interior since ∼ 3900 Ma: Implications for prebiotic molecules: doi.org/10.1023/A:1011895600380
USGS Article: www.usgs.gov/programs/climate....
0:00 How we reconstruct Earth’s past
5:22 Why we study Earth’s past
7:17 How paleoclimate proxies work
9:09 Physical proxies
17:18 Chemical proxies
18:02 Stable isotope chemical proxies
20:53 Carbon isotope example
24:29 Oxygen isotope example
29:27 Sulfur isotope example
33:49 Trace element chemical proxies
38:01 Biochemical proxies (biomarkers)
40:23 Biological proxies (fossils)
41:07 Terrestrial biological proxies
42:48 Aquatic biological proxies
48:10 Honorable mention proxies
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Негізгі бет Ғылым және технология How We Know What Happened in Earth's Past, like Ancient Climate, Geology, & Extinctions | GEO GIRL
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