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Welcome to the Life on Earth Tutorial<\/strong>. This resource is designed to be used in full-screen mode with the table of contents always displayed. To set this mode, click the Expand button in the top right of the header AND click the Navigation Menu button in the top left of the header. Then begin making your way through the tutorial by watching the video below.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"b7414ec5-9465-4b52-999d-b798a2f6b808"},"useSeparator":"auto"},{"content":{"params":{"visuals":{"fit":true,"controls":true},"playback":{"autoplay":false,"loop":false},"l10n":{"name":"Video","loading":"Video player loading...","noPlayers":"Found no video players that supports the given video format.","noSources":"Video is missing sources.","aborted":"Media playback has been aborted.","networkFailure":"Network failure.","cannotDecode":"Unable to decode media.","formatNotSupported":"Video format not supported.","mediaEncrypted":"Media encrypted.","unknownError":"Unknown error.","invalidYtId":"Invalid YouTube ID.","unknownYtId":"Unable to find video with the given YouTube ID.","restrictedYt":"The owner of this video does not allow it to be embedded."},"sources":[{"path":"https:\/\/www.youtube.com\/watch?v=tWH5bxl88f8","mime":"video\/YouTube","copyright":{"license":"U"}}]},"library":"H5P.Video 1.6","metadata":{"contentType":"Video","license":"U","title":"Life on Earth"},"subContentId":"4d246739-7909-4647-9323-ee2790c63b60"},"useSeparator":"auto"},{"content":{"params":{"text":"

**CLARIFICATION: Oxygenic photosynthesis evolved and was active in the oceans from about 3.5 to 2.5 Ga.<\/strong><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"006f5a25-a23a-4f6c-8fa6-82e8fa160639"},"useSeparator":"auto"},{"content":{"params":{"panels":[{"content":{"params":{"text":"

[music]
\nAfter having watched the Early Earth<\/strong> video tutorial, we now have an understanding of how Earth\u2019s early atmosphere, crust, and oceans formed. But how about life? When did that evolve and what was early Earth\u2019s life like?
\n
\nWith a liquid ocean layer present on Earth\u2019s surface, 4.4 billion years ago, the stage was set for the earliest life to form. Why were oceans necessary for life? Early Earth had no oxygen in its atmosphere. That means it also had no ozone layer. Ultraviolet radiation from the Sun readily reached the surface and would have irreparably damaged any biological material. Surface waters in the ocean block ultraviolet radiation, and thus oceans are the perfect place for life to first form. What were these first organisms like? The very simplest single-celled bacteria \u2013 likely ones that could handle extreme conditions, such as high heat and no light \u2013 also known as extremophiles<\/strong>.
\n
\nAll living organisms can be classified as autotrophs or heterotrophs. Heterotrophs <\/strong>acquire their food by eating other organisms. Autotrophs <\/strong>make their own food, usually through a process called photosynthesis<\/strong>. Photosynthesis uses the pigment known as chlorophyll to capture light energy from the Sun, which it then uses to combine abundant surrounding molecules like carbon dioxide and water to synthesize sugar molecules. Respiration <\/strong>is the opposite process and happens when organisms later break down sugar to release its stored energy and use it for growth, reproduction, and energy-intensive metabolic processes. Whether an organism makes its own sugar or gets its sugar by ingesting other organisms, it still must perform respiration to access the stored energy.
\n
\nAlthough photosynthesis is by far the most common form of sugar synthesis at work on Earth today, another process at work where light is absent is called chemosynthesis<\/strong>. Instead of harnessing energy from the sun, chemosynthesis harnesses energy held within chemical bonds of gases and minerals. We see chemosynthesis happening today in a number of dark locations, including deep in underground mines, at the bottom of the seafloor where gases seep out of cracks and sediments, and in caves near sulfur-rich mineral deposits. In all these locations, autotrophs use energy to combine surrounding ingredients and form sugars. Any of these locations could have been the cradles in which early life formed on Earth.
\n
\nIn South African gold mines, in shafts nearly 3 km underground, at temperatures as hot as 120\u00b0F or 49\u00b0C, there are colonies of bacteria surviving without sunlight or oxygen, making their own food from energy stored in chemicals in the rocks, like iron. Other species of bacteria have been found deep in mine shafts and in 1,000-m-deep volcanic rocks along the Columbia River<\/em>. In limestone caves, near volcanic sulfur-rich hot springs, bacteria capture energy from hydrogen sulfide gas and use that energy to synthesize sugar. Sulfuric acid is one of the toxic byproducts, and these bacteria live in highly acidic mucous-rich mats attached to the cave walls. The mats are called snottites<\/strong>. This example is from Cueva de Villa Luz in Tabasco, Mexico<\/em>. These snottites have acid drops at their tips, with a pH of 0.
\n
\nIn hydrothermal vents and hydrocarbon seeps on the bottom of the seafloor, bacteria capture energy from hydrogen sulfide or methane gases and use that energy to synthesize sugar. These bacteria provide the base of an exotic and diverse food web.
\n
\nPause now. [music]
\n
\nOne of the first experiments to simulate the formation of the basic molecules of life was done by Stanley Miller as a graduate student at the University of Chicago in the early 1950s. Into a closed system of flasks, Miller put methane, ammonia, hydrogen gas, and water vapor\u2014all materials that would have been major components of the early Earth\u2019s atmosphere. He warmed a soup of these chemicals, circulated them through a region where they were subjected to electric sparks (simulating lightning), and cooled them and returned the products to the soup. Within a few days, the soup was a brown slime that contained amino acids, the building blocks of proteins. Although scientists no longer think the components of his experiment were an exact match to early Earth\u2019s environment, Miller\u2019s experiment showed scientists that it was possible to create, through natural processes, the building blocks needed for life. Many scientists around the world are currently studying the synthesis of living cells and creating life in its simplest forms from building blocks that would have been available in early Earth.
\n
\nWhen did life first evolve on planet Earth? Oxygen isotope ratios in 4.4-billion-year-old zircon minerals indicate temperatures on the surface would have been cool enough for liquid water to be stable. Since life requires water, 4.4 billion years represents a possible oldest date for life on Earth. A 3.85-billion-year-old rock from Greenland was found to have carbon isotope ratios suggestive of microbial activity. However, the first fossil evidence we have are stromatolite mounds found in 3.7-billion-year-old rocks from Greenland. Stromatolite mounds form by successive layers of photosynthesizing cyanobacterial mats growing in a coastal environment and doming upwards toward the light. Each layer traps sand within it, ultimately blocking the light, requiring new layers to form atop the old ones. The cyanobacteria are protected from the ultraviolet rays of the sun by the thick mucus coating in which they live. This image shows what fossilized stromatolite mounds look like. Today, photosynthesis is primarily oxygenic: producing oxygen as a waste product. However, the earliest form of photosynthesis was not an oxygen-producing one.
\n
\nWhy does the evolution of oxygenic photosynthesis matter? Advanced life can evolve only in the presence of large amounts of atmospheric oxygen, and oxygenic photosynthesis is the dominant natural process at work on Earth that produces that oxygen. What evidence would we look for to tell us oxygenic photosynthesis had evolved? Minerals such as manganese or iron oxides that form through chemical reactions between oxygen gas and either dissolved metals in the oceans or metals in weathering surface rocks on land. While as far back as 3.23 billion years ago there appear to be small localized precipitations of iron oxide minerals on the seafloor, now visible in layered rocks known as Banded Iron Formations, additional evidence suggests those were formed as a byproduct of anoxygenic photosynthesis by bacteria that used iron as an electron donor.
\n
\nHowever, the largest known deposit of banded iron formations have been determined to be due to a large scale release of oxygen by photosynthetic stromatolite colonies. These deposits are about 2.5 billion years old and can be found today in the Pilbara region of Western Australia. These rock layers are now the source of the world\u2019s largest iron ore mines. Here are two samples from the Pilbara Desert, Australia. On the left you see small fossilized stromatolites (the oxygen producers) and next to it the banded iron.
\n
\nOnce the majority of the dissolved iron in the oceans was removed through iron oxide precipitation, or \u201crusting\u201d, oxygen was free to mix through the oceans and bubble up and enter the atmosphere, where it became available for the oxidation of atmospheric gases and dissolved metals in weathering surface rocks and rivers and lakes. The oldest evidence we find of this activity and thus oxygen gas accumulating in our atmosphere are from the north shore of Lake Huron, Ontario, Canada: Red Beds (iron-oxide-rich rocks formed on Earth\u2019s surface) dated between 2.2 and 2.4 billion years old.
\n
\nWe call this period of time, about 2.3 billion years ago, when oxygen gas began to accumulate in the atmosphere for the first time in amounts as large as 1% of current values, the Great Oxygenation Event. It was over 1 billion years later before another large oxygen-increase event brought oxygen levels up to today\u2019s levels. It took that long for the oxygen to complete its chemical reactions with other atmospheric gases and dissolved metals on Earth\u2019s surface. After that work was done, oxygen gas could begin to accumulate in amounts necessary to support more advanced life.
\n
\nPause now. [music]
\n
\nThe first step towards that advanced life was developing a nucleus and sexual reproduction. The oldest evidence we have of this evolution are fossils of Grypania spiralis<\/em> \u2013 found in 2.1-billion-year-old banded-iron formations in Michigan. However, it was quite a long time before organisms like these really proliferated and cooperated to create multicelled life, because it had to wait until the oxygen levels in the atmosphere built up enough to support the increased metabolism that goes along with multicelled life. The stromatolites and other photosynthesizing bacteria still had a lot of work to do. How much work? The oldest evidence of multicelled life was discovered in fossils of soft-bodied marine organisms in 600-million-year old rocks in the Ediacaran Hills of Australia. That\u2019s 4 billion years after Earth formed, and in the last 1\/9 of Earth\u2019s history.
\n
\nAfter oxygen levels rose to current levels and multicelled life evolved, evolution really took off. 544 million years ago, we see the first evidence of hard parts, thus contributing to many orders of magnitude more fossils forming as hard parts make fossilization much easier. It was also the beginning the Age of the Trilobites \u2013 crab-like animals with exoskeletons that scuttled across the seafloor. Ammonites came next, a nautilus-like cephalopod -- imagine a giant octopus-like organism living in an ornate hard shell and floating at various depths within the water column. The first vertebrates \u2013 jawless fish with cartilaginous skeletons \u2013 evolved about 520 million years ago. Again, the evidence for this timeline comes from fossils we find in rocks that we date through radiometric dating. Watch the video tutorial on radiometric dating for more information on that process.
\n
\n438 million years ago is our first evidence we have of organisms moving onto land \u2013 including the first plants and insects.
\n
\n245 million years ago was the largest mass extinction on the planet, during which the trilobites and many other early forms of life went extinct. Dinosaurs evolved soon after and dominated the planet during the Age of the Dinosaurs, which lasted from 230 to 65 million years ago.
\n
\nEarly mammals co-existed with the dinosaurs, but after the dinosaurs went extinct, 65 million years ago, mammals continued to evolve to fill the now-empty niches left behind by the dinosaurs.
\n
\n50 million years ago, some land mammals returned to the ocean, evolving into whales, sea lions, seals, and other marine mammals.
\n
\nThe earliest monkeys and apes evolved 40 million years ago.
\n
\nAnd the oldest evidence we have of early bipedal hominids is 4 million years ago.
\n
\n2 million years ago we began the period of cyclical ice ages that we are coming out of today. The last ice age ended only 20,000 years ago.
\n
\nPause now. [music]
\n
\nUnderstanding the magnitude and scale of Earth\u2019s history is a challenging task for organisms that live only on average 75 years and that are primarily focused on events that happened in the last week or month. But it\u2019s a challenge that must be tackled if we want to understand the important processes that created the world around us and continue to shape it today.
\n[music]
\n
\n[end credits]
\n
\nEarth Formation Series:
\nPart I: Earth Formation
\nPart II: Radiometric Dating
\nPart III: Density
\nPart IV: Early Earth
\nPart V: Life on Earth
\n
\nLife on Earth Produced by Katryn Wiese
\nCopyright: Creative Commons Attribution-NonCommercial-ShareAlike 3.0
\n
\nAll media produced by Katryn Wiese unless indicated below:
\n*Intro and exit music: used with permission (c) Alexis Harte (www.alexisharte.com)
\n*Rain on water: CC-BY-SA 2.0. Issy Witcomb
\n*Archaebacteria: Single image: Methanosarcina thermophila. Set of 4 vent bacteria: micrograph. Both images: \u00a9 Stephen H. Zinder, Cornell University Department of Microbiology. NOAA
\n*Hydrothermal vent - black smokers and sulfur-mineralized vents (2 images): Public Domain. NOAA
\n*South African Gold Mine: ~2 miles below the ground - Duane Moser next to fracture zone (white area) where one-of-a-kind bacteria were found: \u00a9 Li-Hung Lin.
\n*Cueva de Villa Luz Snottites (Tabasco, Mexico): Snottite cluster in Snot Heaven. \u00a9 Kenneth Ingham, used with permission, http:\/\/keninghamphoto.com
\n*Transmission electron micrograph of Thermus bacteria isolated from Witswatersand gold mine. \u00a9 Hailiang Dong and Gordon Southam at Northern Arizona University.
\n*Columbia River Basalt Bacteria: Public Domain. NASA.
\n*Indian Ocean Basalt: Public Domain. NOAA\/OER.
\n*Cueva de Villa Luz Acid Pool: \u00a9 Getty\/National Geographic.
\n*Urey-Miller Experiment: GFDL, CC-BY-SA: Attribution: A. Knoll
\n*Amino Acid structure: Public Domain
\n*Jack Hills Zircon: \u00a9 John Valley, University of Wisconsin.
\n*Greenland map: Google Earth. Imagery \u00a9 2017 Data SIO, NOAA, US Navy, NGA, GEBCO, IBCAO, Landsat\/Copernicus, USGS.
\n*Stromatolite Fossils from Greenland, 3.7 Ga, A. Nutman et al.\/Nature \u00a9.
\n*Stromatolite formation cartoon, author unknown. Embedded fossil cyanobacteria filament: J. William Schopf \u00a9.
\n*Stromatolite fossil from Houston Museum of Natural History: CC-0-1.0 Universal Public Domain.
\n*Map of Huronian Supergroup: Ohio State Govt. Website.
\n*Gripania spiralis fossils: 3 images: Negaunee Fe-FM, Empire Mine, Marquette Co UP Michigan, CC BY 2.0. Attribution: James St. John.
\n*Ediacaran fossils: Dickensonia costata, CC-BY-SA 3.0 Attribution: Verisimilus. Spiggina floundensi, CC BY 2.5, Attribution: Merikanto; http:\/\/www.ga.gov.au\/ausgeonews\/ausgeonews200512\/timescales.jsp
\n*Ediacaran Hills map of Australia \u2013 Australian Government.
\n*Trilobite cartoon: Public Domain. Original Author: 1916, The Wonderful Paleo Art of Heinrich Harder
\n*Lampreys: author unknown.
\n*Pikaia gracilens: from the Burgess Shale on display at the Smithsonian in Washington, DC. Public Domain.
\n*Meganeura. CC-BY-NC-ND Mus\u00e9um de Toulouse.
\n*Life Moves Onto Land Mural - on display in Story of Time and Life Exhibit, City College of San Francisco. Artists: Maren Van Duyn, Caroly Van Duyn (1990). Photo by K. Wiese.
\n*Early mammal, Jugulator amplissimus, CC BY SA 4.0. Attribution: Julio Lacerda.
\n*Feeding humpback whales. Public Domain. Attribution: Evadb.
\n*Manatee: CC-BY-2.0. Attribution: Keith Ramos, US Fish and Wildlife Service.
\n*Early Apes: The common chimpanzee (Pan troglodytes) Creative Commons \/ B\u00f6hringer.
\n*Early Hominids: 3 images from display in the Hall of Human Origins at Smithsonian Institution. Illustration of Homo erectus group: Artist John Gurche. http:\/\/humanorigins.si.edu. Australopithecus afarensis - CC BY SA 3.0 Photo by Nachosan
\n*Ice age graph: Public Domain. NOAA.
\n*Agassiz Ice Cap: CC BY SA 3.0. Paul Gierszewski<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"e3513460-f118-4927-ae8d-39af504a00cb"},"title":"Life on Earth Video Script (for review as needed)"}],"hTag":"h2"},"library":"H5P.Accordion 1.0","metadata":{"contentType":"Accordion","license":"U","title":"Life on Earths Video Script (for review as needed)"},"subContentId":"a7badb4b-240d-4549-b78f-9d4cee88957f"},"useSeparator":"enabled"},{"content":{"params":{"text":"

When done with the video above, continue through the remaining pages of this book to review content and images from the video, explore some content more deeply, and test your understanding through interactive ungraded quiz questions. The final page of the tutorial is a list of Additional Resources for students who want to dig even deeper into some of the video contents. When you've reached that page, you're done.<\/p>\n\n

To navigate to the remaining pages of this tutorial, use the arrow keys that appear in the header and footer. Or use the table of contents navigation menu, which you can toggle open or closed by using the button on the top left of the screen. <\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"d8d9472b-f841-42c5-86a5-8c3321b90217"},"useSeparator":"enabled"}]},"library":"H5P.Column 1.18","subContentId":"d7bf0253-f2f2-423c-a80e-6146a7588f15","metadata":{"contentType":"Column","license":"U","title":"Video: Life on Earth"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","alt":"Scaled timeline of solar system and Earth formation","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-65ed20302fcd0.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":2402,"height":2154},"title":"Scaled timeline of solar system and Earth formation"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"e15b75b3-ebe9-4e4a-bc57-35f89154b51f"},"useSeparator":"auto"},{"content":{"params":{"text":"

Above image: scaled timeline of the history of the Universe from 13.8 Ga to today. (Katryn Wiese, CC BY NC SA)<\/span><\/span><\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"139d104f-b9d1-4c29-954a-d1e7a5c59c59"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"Scaled Timeline"},"subContentId":"8071ec43-c49c-4e69-9aca-92dfd43ef27b"},{"params":{"content":[{"content":{"params":{"text":"

\n
Below is a timeline of Earth's History events. Notice that the oldest event in this history is listed at the bottom, youngest at the top. To review this history, scroll to the bottom of the page and start there. Read from the bottom up!<\/strong><\/p>\n\n
Notes:<\/strong>
\n*Ka<\/strong> = kilo annum = thousand years ago
\n*Ma<\/strong> = Mega annum = million years ago (my<\/strong> = million of years | My BP<\/strong> = Millions of years before present)
\n*Ga<\/strong> = Giga annum = billion years ago<\/p>\n\n
\n
\n\t
10-25 Ka <\/strong>-- Wisconsin ice age (most recent one; land bridges form and humans migrate from Asia into North America)<\/li>\n\t
100-300 Ka<\/strong> -- Homo Sapiens first appear.<\/li>\n\t
400 Ka<\/strong> -- San Francisco Bay forms.<\/li>\n\t
1.6 Ma <\/strong>-- Period of frequent ice ages begins and continues to today.<\/li>\n\t
2-4 Ma<\/strong> -- Ancient Hominids first appear.<\/li>\n\t
50-25 Ma<\/strong> -- San Andreas Fault forms as North American margin stops subducting.<\/li>\n\t
63 Ma <\/strong>-- Primates evolve.<\/li>\n\t
65 Ma<\/strong> -- Dinosaurs and other organisms go extinct making the way for the Age of Mammals.<\/li>\n\t
145 Ma<\/strong> -- First mammals, including platypus, shrews, and opossums.<\/li>\n\t
152 Ma<\/strong> -- First birds evolve from small, fast-running dinosaurs.<\/li>\n\t
225 Ma<\/strong> -- Pangaea, the most recent supercontinent completes its formation, and then begins its breakup (to create the Atlantic Ocean). Two halves: Gondwanaland (Australia, India, Africa, S. American, Antarctica) and Laurasia (N. America, Greenland, Europe, and Asia).<\/li>\n\t
230 Ma<\/strong> -- First dinosaurs, reptiles that distinguished themselves by standing upright on two legs.<\/li>\n\t
240 Ma<\/strong> -- First vertebrates to fly \u2013 the Pterosaurs, dinosaur cousins.<\/li>\n\t
245 Ma<\/strong> -- The largest mass extinction in Earth\u2019s history. Over 75% of all marine groups eliminated, making way for the Age of Dinosaurs<\/li>\n\t
350-290 Ma <\/strong>-- Giant Swamp Forests thrived in lowlands at the edges of rivers and seas (like today's Louisiana bayous). Tropical climates encouraged dense growth of ferns, tree ferns, and club-mosses. The buried material from these forests eventually became much of the world\u2019s current coal resources.<\/li>\n\t
400 Ma<\/strong> -- First lungs.<\/li>\n\t
430 Ma <\/strong>-- First jawed fish.<\/li>\n\t
438 Ma<\/strong> -- First plants move onto land, followed within 10 million years by animals (aquatic scorpions and other arthropods).<\/li>\n\t
480 Ma<\/strong> -- Large continent known as Gondwanaland forms from the collision of Australia, India, Africa, South America, and Antarctica. Pacific Plate subducts under North America\u2019s western margin. The western margin grows through accretion of oceanic rocks and islands (terranes).<\/li>\n\t
520 Ma<\/strong> -- First vertebrates (cartilaginous fish with tails and fins).<\/li>\n\t
540 Ma<\/strong> -- First organisms with hard parts. Beginning of the Age of Trilobites. Also existing early on were brachiopods and ammonites.<\/li>\n\t
600 Ma<\/strong> -- Ediacaran fauna, soft-bodied marine animals that get their food primarily from small algae.<\/li>\n\t
~700 Ma<\/strong> -- Oxygen levels reach modern-day levels (21% Oxygen).<\/li>\n\t
700 to 800 Ma<\/strong> -- Our oldest multi-celled animals: sponges.<\/li>\n\t
1 Ga<\/strong> -- Red Beds stop forming in large amounts and free oxygen begins to accumulate in the atmosphere. The atmosphere begins to evolve to one closer to today\u2019s. Eventually enough oxygen accumulates in the atmosphere that UV radiation interacted with it in the upper atmosphere to produce ozone, a gas that then acts as a UV shield, protecting life on Earth\u2019s surface.<\/li>\n\t
1.7 Ga to 2.1 Ga<\/strong> -- Gripania spiralis<\/em>, the first oldest fossil of multicelled eukaryotes.<\/li>\n\t
2.1 to 2.7 Ga<\/strong> -- First single-celled Eukaryotes evolve through endosymbiosis (oldest date comes from a molecular clock)<\/li>\n\t
2.3 Ga<\/strong> -- Great Oxygenation Event: Red Beds form on land. These beds are land-based rust piles that take the place of the oceanic banded iron formations as free oxygen now leaves the oceans and enters the atmosphere. The Red Beds absorb most of the available oxygen. <\/li>\n\t
3.5 to 2.5 Ga<\/strong> -- Oxygenic photosynthesis (see chemical reaction below).
\n\tOcean and atmospheric chemistry begins to change as oxygen is added and carbon dioxide removed. Largest deposit of Banded Iron Formations (BIFs). Earth\u2019s oceans would have had a lot of dissolved iron, due to the accumulation of hundreds of millions of years of rock weathering and underwater volcanic eruptions. Oxygenic photosynthesis produced sufficient oxygen gas to readily and quickly combine with the iron to form large deposits of rust.<\/li>\n<\/ul>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"5950d99f-08fc-4f5d-9ee4-c28d0f96fc0d"},"useSeparator":"auto"},{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-62b743b18ff28.png","mime":"image\/png","copyright":{"license":"U"},"width":1278,"height":69},"alt":"chemical reaction that represents oxygenic photosynthesis","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"chemical reaction that represents oxygenic photosynthesis"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"638a5e46-a8d2-43df-a6f3-c7af528b9b0f"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above image: photosynthesis reaction (water + carbon dioxide + sunlight \u2192 sugar + oxygen) (Katryn Wiese, CC BY NC SA<\/em><\/p>\n\n
\n\t
3.7 Ga<\/strong> -- Earliest evidence of stromatolites: layered rock mounds formed in shallow oceans as mats of cyanobacteria dome upward to capture energy from sunlight to produce sugar through anoxygenic photosynthesis. Live in mucous layers to avoid UV-radiation damage to the sun.<\/li>\n\t
3.85 Ga<\/strong> -- Earliest evidence of microbial activity (carbon isotope ratios). This early life likely lived in the oceans where they were hidden from the sun\u2019s ultraviolet rays (no ozone layer yet, because no oxygen in the atmosphere). These early bacteria were known as prokaryotes: single celled organisms with no nucleus, otherwise known as bacteria. These early life forms were likely chemosynthetic, making food from energy derived from gases emitted at hydrothermal vents on the bottom of the seafloor.<\/li>\n<\/ul>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"d1031458-7097-48d8-b6aa-2ddf44538d65"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"Brief History of Earth"},"subContentId":"02995c41-e4dc-46f0-98df-c98e0bcfb1d8"},{"params":{"content":[{"content":{"params":{"imageSlides":[{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c819cf5d8c7.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":3648,"height":2736},"alt":"Stromatolites in Sharks Bay Australia","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Stromatolites in Sharks Bay Australia"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"8aefda37-0cdb-4401-b156-bd81743a5015"}},"library":"H5P.ImageSlide 1.1","subContentId":"35487aed-da16-48c5-802e-d5f6ac33f053","metadata":{"contentType":"Image Slide","license":"U","title":"Stromatolites, Sharks Bay Australia"}},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c819ad2fe54.png","mime":"image\/png","copyright":{"license":"U"},"width":482,"height":393},"alt":"How stromatolites form","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"How stromatolites form"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"bb2139f7-05d3-4c16-ba87-8251e9691f9f"}},"library":"H5P.ImageSlide 1.1","subContentId":"40cf6726-9f38-4cb8-8ab9-2a5424f18f49","metadata":{"contentType":"Image Slide","license":"U","title":"How Stromatolites Form"}},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c83f4559ef4.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1283,"height":962},"alt":"Fossil stromatolites","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Fossil stromatolites"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"c6c1eeef-1c77-4aee-9bd7-2201905d958c"}},"library":"H5P.ImageSlide 1.1","subContentId":"2b6094e3-322b-463e-a73d-14ad3dfb981f","metadata":{"contentType":"Image Slide","license":"U","title":"Stromatolite fossil"}},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c81a2a8be14.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":3648,"height":2736},"alt":"Stromatolite algal mats growing in a tank, Sharks Bay, Australia","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Stromatolite algal mats growing in a tank, Sharks Bay, Australia"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"744db3ce-a25d-4628-b321-da984eb8e86b"}},"library":"H5P.ImageSlide 1.1","subContentId":"9bcded9e-c6f3-4430-b240-933e2032d545","metadata":{"contentType":"Image Slide","license":"U","title":"Living stromatolites"}}],"aspectRatioMode":"auto","aspectRatio":{"aspectWidth":4,"aspectHeight":3},"a11y":{"nextSlide":"Next Image","prevSlide":"Previous Image","gotoSlide":"Go to image %slide"}},"library":"H5P.ImageSlider 1.1","metadata":{"contentType":"Image Slider","license":"U","title":"Stromatolites"},"subContentId":"a52a38fe-44f4-4836-9af3-306bf801c76f"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above is an image gallery<\/strong> that provides visuals of stromatolites. Under each image are dots showing how many images are in the gallery. You can navigate between images by clicking on the dots or by using the arrow keys on the edges of the images. Captions for each image are listed below.<\/p>\n\n
\n\t
Modern-day stromatolites in Sharks Bay Australia (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n\t
How stromatolites form (source unknown)<\/li>\n\t
Modern-day stromatolite algal mats growing in a tank, Sharks Bay, Australia (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n\t
Fossilized stromatolites from the Kootenai Falls area of Montana. (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n<\/ol>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"38711eea-c414-4d55-a24d-5fd272ae787e"},"useSeparator":"auto"},{"content":{"params":{"text":"
Stromatolites are mounds created by algal mats of cyanobacterial. We first see them in the fossil record 3.5 Ga. And they still exist today as the top and bottom images on this page demonstrate. Modern-day stromatolites perform oxygenic photosynthesis, whereas their earliest ancestors had not yet developed this process. They did, however, use sunlight to make sugars through anoxic photosynthesis, and so they needed to live close to the surface of the oceans. To prevent themselves from being damaged by the Sun's UV radiation (no ozone layer), they collected a layer of sand around them. Each generation grew upwards to form a new layer.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"37e31316-ac71-48c3-9016-b15f172cc9da"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"34750756-85be-45c3-8aad-6e0cd4efda6a","metadata":{"contentType":"Column","license":"U","title":"Stromatolites"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","alt":"Oxygen throughout Earth's History","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-65f10ee44f966.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1963,"height":1274},"title":"Oxygen throughout Earth's History"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"2bbb306d-d8e3-4eea-abf1-cd04cb2e6641"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above image: Oxygen in Earth\u2019s atmosphere since Earth\u2019 formation. (Katryn Wiese, CC BY NC SA)<\/em><\/p>\n\n
Oxygen likely first began being produced through oxygenic photosynthesis, about 3.5 Ga. It either combined with dissolved iron to produce iron oxide minerals (rust) that settled to the seafloor and were buried OR it bubbled out into the atmosphere and was immediately used up in oxidizing the atmospheric gases. By 2.3 Ga, most of the dissolved iron in the oceans had been removed, and oxygen was starting to accumulate at levels of 1% of today\u2019s Oxygen levels in the atmosphere. We call this the Great Oxygenation Event<\/strong>. Oxygen in the atmosphere allowed for the first iron oxide minerals to form in surface rocks (above sea level). By about 700 Ma, the atmospheric gases were sufficiently oxidized, and oxygen began to accumulate in larger amounts in the atmosphere, bringing it to current day levels and allowing an ozone layer to form in the stratosphere<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"e34363e3-33cf-48b0-a2a7-ccb8fc39bea2"},"useSeparator":"auto"},{"content":{"params":{"text":"
Below is a set of test-your-understanding questions<\/strong>. Below each question are dots showing how many questions are in the set. You can navigate between questions by clicking on the dots or by using the arrow keys to the right of the dots. Use the Check button to check your answers, and if needed, use the Retry button to try again.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"e9b23616-31c3-4056-9989-b95167bbc9ee"},"useSeparator":"auto"},{"content":{"params":{"introPage":{"showIntroPage":false,"startButtonText":"Start Quiz","introduction":""},"progressType":"dots","passPercentage":100,"questions":[{"params":{"media":{"disableImageZooming":false},"answers":[{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Asteroids<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Comets<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Original nebula debris<\/div>\n"},{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Photosynthesis<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
Volcanoes<\/div>\n"}],"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"type":"auto","singlePoint":false,"randomAnswers":false,"showSolutionsRequiresInput":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false,"passPercentage":100,"showScorePoints":true},"UI":{"checkAnswerButton":"Check","submitAnswerButton":"Submit","showSolutionButton":"Show solution","tryAgainButton":"Retry","tipsLabel":"Show tip","scoreBarLabel":"You got :num out of :total points","tipAvailable":"Tip available","feedbackAvailable":"Feedback available","readFeedback":"Read feedback","wrongAnswer":"Wrong answer","correctAnswer":"Correct answer","shouldCheck":"Should have been checked","shouldNotCheck":"Should not have been checked","noInput":"Please answer before viewing the solution","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
Which of the following is the primary source (only source) of oxygen to Earth's atmosphere?<\/p>\n"},"library":"H5P.MultiChoice 1.16","metadata":{"contentType":"Multiple Choice","license":"U","title":"Oxygen"},"subContentId":"3e28668d-a257-425a-abc4-56451430b444"},{"params":{"media":{"disableImageZooming":false},"answers":[{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
4.6 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
4.4 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
4.0 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
3.5 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
3 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
2.5 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
2 Ga<\/div>\n"},{"correct":false,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
1.5 Ga<\/div>\n"},{"correct":true,"tipsAndFeedback":{"tip":"","chosenFeedback":"","notChosenFeedback":""},"text":"
700 Ma<\/div>\n"}],"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableSolutionsButton":true,"enableCheckButton":true,"type":"auto","singlePoint":false,"randomAnswers":false,"showSolutionsRequiresInput":true,"confirmCheckDialog":false,"confirmRetryDialog":false,"autoCheck":false,"passPercentage":100,"showScorePoints":true},"UI":{"checkAnswerButton":"Check","submitAnswerButton":"Submit","showSolutionButton":"Show solution","tryAgainButton":"Retry","tipsLabel":"Show tip","scoreBarLabel":"You got :num out of :total points","tipAvailable":"Tip available","feedbackAvailable":"Feedback available","readFeedback":"Read feedback","wrongAnswer":"Wrong answer","correctAnswer":"Correct answer","shouldCheck":"Should have been checked","shouldNotCheck":"Should not have been checked","noInput":"Please answer before viewing the solution","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again."},"confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"question":"
At approximately which of the following times in Earth's history did oxygen levels reach the current level or higher?<\/p>\n"},"library":"H5P.MultiChoice 1.16","metadata":{"contentType":"Multiple Choice","license":"U","title":"Oxygen at highest"},"subContentId":"935e0f85-4e8a-4f4f-929a-87739926c878"}],"disableBackwardsNavigation":false,"randomQuestions":false,"endGame":{"showResultPage":true,"showSolutionButton":false,"showRetryButton":true,"noResultMessage":"Finished","message":"Your result:","scoreBarLabel":"You got @finals out of @totals points","overallFeedback":[{"from":0,"to":100}],"solutionButtonText":"Show solution","retryButtonText":"Retry","finishButtonText":"Finish","submitButtonText":"Submit","showAnimations":false,"skippable":false,"skipButtonText":"Skip video"},"texts":{"prevButton":"Previous question","nextButton":"Next question","finishButton":"Finish","submitButton":"Submit","textualProgress":"Question: @current of @total questions","jumpToQuestion":"Question %d of %total","questionLabel":"Question","readSpeakerProgress":"Question @current of @total","unansweredText":"Unanswered","answeredText":"Answered","currentQuestionText":"Current question","navigationLabel":"Questions"},"override":{"checkButton":true,"showSolutionButton":"off","retryButton":"on"}},"library":"H5P.QuestionSet 1.20","metadata":{"contentType":"Question Set","license":"U","title":"Test Your Understanding"},"subContentId":"06ba3982-d3bc-417e-901d-4660196bed33"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"e737b394-139c-47e5-a11f-4fcf1c02e38f","metadata":{"contentType":"Column","license":"U","title":"Oxygen Through Time"}},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-67aaa7134bf85.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":750,"height":450},"alt":"BIF Formation","title":"BIF Formation"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"538b0cb6-d972-401d-8113-07b76ddcbb23"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above image: Role of hydrothermal circulation and stromatolites in banded iron formation: alternating bands of iron-rich and silica-rich mud, formed as oxygen combined with dissolved iron. (C. Bentley, CC BY SA 4.0)<\/em><\/p>\n\n
\n
The first oxygen gas to form combined with dissolved iron to produce iron oxide minerals (rust) that settled to the seafloor and were buried. We call the rocks that formed at this time, with alternating layers of hematite and magnetite (both iron oxides) and red chert (precipitated silica), Banded Iron Formation.<\/strong><\/p>\n\n
\n
Below is an image gallery<\/strong> that provides visuals of banded iron formatoins. Under each image are dots showing how many images are in the gallery. You can navigate between images by clicking on the dots or by using the arrow keys on the edges of the images. Captions for each image are listed below.<\/p>\n\n
\n\t
Banded Iron Formation specimen from Upper Michigan. (Wilson44691 -- Public Domain)<\/em><\/li>\n\t
Polished BIF in the Natural History Museum of New York (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n\t
Karajini Gorge banded iron layers, Pilbara Desert, Australia (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n\t
Karajini Gorge iron layers, Pilbara Desert, Australia (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n\t
Tom Price Iron Ore Mining, Pilbara Desert, Australia (Katryn Wiese, CC BY NC SA)<\/em><\/li>\n<\/ol>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"c76eb146-b20d-45c6-a44a-f645ac63d86b"},"useSeparator":"auto"},{"content":{"params":{"imageSlides":[{"params":{"image":{"params":{"decorative":false,"contentName":"Image","expandImage":"Expand Image","minimizeImage":"Minimize Image","file":{"path":"images\/file-6681f2333218e.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1599,"height":1100},"alt":"Banded Iron Formation from Michigan","title":"Banded Iron Formation from Michigan"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"4a696378-276d-46c6-9389-7c210cd45436"}},"library":"H5P.ImageSlide 1.1","metadata":{"contentType":"Image Slide","license":"U","title":"BIF"},"subContentId":"6390e4b1-68e7-4b0d-8261-aa524380bddf"},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c8416a3e084.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":722,"height":962},"alt":"BIF from a NY Museum of Natural History","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"BIF from a NY Museum of Natural History"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"196a80a1-f3c1-4223-9933-4ad553f69ce2"}},"library":"H5P.ImageSlide 1.1","metadata":{"contentType":"Image Slide","license":"U","title":"BIF from a NY Museum of Natural History"},"subContentId":"bcc21aea-d2b8-47f8-b6c6-0738b241d69d"},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c83c86849f9.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":1286,"height":962},"alt":"Karajini Gorge","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Karajini Gorge"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"9dca4a93-87e6-48f7-b80e-9688eb9886e8"}},"library":"H5P.ImageSlide 1.1","metadata":{"contentType":"Image Slide","license":"U","title":"Karajini Gorge"},"subContentId":"c859dc7c-4148-4b8e-9e06-773c3803c6e8"},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c84152a47db.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":1283,"height":962},"alt":"Karajini Gorge","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Karajini Gorge"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"01e1ef8c-8b3f-4a64-a343-02633ad93365"}},"library":"H5P.ImageSlide 1.1","metadata":{"contentType":"Image Slide","license":"U","title":"Karajini Gorge"},"subContentId":"b628f5c3-1d3b-4d17-9b77-adcfbe7a2cf5"},{"params":{"image":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64c83dbf65062.JPG","mime":"image\/jpeg","copyright":{"license":"U"},"width":1283,"height":962},"alt":"Tom Price, Australia Iron Mining","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Tom Price, Australia Iron Mining"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"f72fe33a-5f2e-4c5f-8c78-787d2b2dbb2d"}},"library":"H5P.ImageSlide 1.1","metadata":{"contentType":"Image Slide","license":"U","title":"Tom Price, Australia Iron Mining"},"subContentId":"7f76d6ab-474d-433c-a095-6f3921efdc3e"}],"aspectRatioMode":"auto","aspectRatio":{"aspectWidth":4,"aspectHeight":3},"a11y":{"nextSlide":"Next Image","prevSlide":"Previous Image","gotoSlide":"Go to image %slide"}},"library":"H5P.ImageSlider 1.1","metadata":{"contentType":"Image Slider","license":"U","title":"BIFs"},"subContentId":"28fc77bd-c8f6-4110-86d0-64a93191d0f7"},"useSeparator":"auto"},{"content":{"params":{"text":"
\n<\/ol>\n\n
Karajini Gorge is a National Park in the Pilbara Desert of Australia. The layers you see in the above images are a 2.5-Ga banded iron formation (BIF). There's so much banded iron in the Pilbara Desert that it's one of the largest Iron ore mining regions of the world as shown in the image from Tom Price, Australia. <\/p>\n\n
Wonder how the separate layers form in a BIF (when the hematite (aka rust) and silica (aka chert) that make up the layers are laid down together)? See video footage below from the Exploratorium of how materials separate into layers after deposition.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"942161d6-307e-4a36-a1a7-557fd80ff0d1"},"useSeparator":"auto"},{"content":{"params":{"visuals":{"fit":true,"controls":true},"playback":{"autoplay":false,"loop":false},"l10n":{"name":"Video","loading":"Video player loading...","noPlayers":"Found no video players that supports the given video format.","noSources":"Video is missing sources.","aborted":"Media playback has been aborted.","networkFailure":"Network failure.","cannotDecode":"Unable to decode media.","formatNotSupported":"Video format not supported.","mediaEncrypted":"Media encrypted.","unknownError":"Unknown error.","invalidYtId":"Invalid YouTube ID.","unknownYtId":"Unable to find video with the given YouTube ID.","restrictedYt":"The owner of this video does not allow it to be embedded."},"sources":[{"path":"https:\/\/youtu.be\/CxWhSkHjLnM","mime":"video\/YouTube","copyright":{"license":"U"}}]},"library":"H5P.Video 1.6","metadata":{"contentType":"Video","license":"U","title":"Gneissic Layering"},"subContentId":"b93fe084-babf-4f17-a228-ed041467314e"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","metadata":{"contentType":"Column","license":"U","title":"3.5 Ga Banded Iron Formations"},"subContentId":"5e685502-24ed-4db4-bb52-2805ff34a858"},{"params":{"content":[{"content":{"params":{"decorative":false,"contentName":"Image","file":{"path":"images\/file-64b48757f0d1d.jpg","mime":"image\/jpeg","copyright":{"license":"U"},"width":1800,"height":3814},"alt":"Step-by-step guide to the evolution of humans","expandImage":"Expand Image","minimizeImage":"Minimize Image","title":"Step-by-step guide to the evolution of humans"},"library":"H5P.Image 1.1","metadata":{"contentType":"Image","license":"U","title":"Untitled Image"},"subContentId":"f694d1ea-08f9-4375-9d67-e53c39d8b953"},"useSeparator":"auto"},{"content":{"params":{"text":"
Above image is a visual step-by-step guide to the evolution of humans. (Mark Belan, Visual Capitalist<\/a>) To see the image big enough to read, follow source link.<\/em><\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"d8343527-8285-4a6f-8c4e-213222bad7fe"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"72d9947d-30be-4f90-9bbf-a2c23d99e9ba","metadata":{"contentType":"Column","license":"U","title":"Becoming Human"}},{"params":{"content":[{"content":{"params":{"text":"
\n
Below is a set of test-your-understanding questions<\/strong>. Below each question are dots showing how many questions are in the set. You can navigate between questions by clicking on the dots or by using the arrow keys to the right of the dots. Use the Check button to check your answers, and if needed, use the Retry button to try again.<\/p>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"a4773a4c-50e4-4d2f-8d64-e4843c5911bf"},"useSeparator":"auto"},{"content":{"params":{"introPage":{"showIntroPage":false,"startButtonText":"Start Quiz","introduction":""},"progressType":"dots","passPercentage":100,"questions":[{"params":{"media":{"disableImageZooming":false},"text":"
Life first evolved<\/p>\n","overallFeedback":[{"from":0,"to":100}],"showSolutions":"Show solution","tryAgain":"Retry","checkAnswer":"Check","submitAnswer":"Submit","notFilledOut":"Please fill in all blanks to view solution","answerIsCorrect":"':ans' is correct","answerIsWrong":"':ans' is wrong","answeredCorrectly":"Answered correctly","answeredIncorrectly":"Answered incorrectly","solutionLabel":"Correct answer:","inputLabel":"Blank input @num of @total","inputHasTipLabel":"Tip available","tipLabel":"Tip","behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"autoCheck":false,"caseSensitive":true,"showSolutionsRequiresInput":true,"separateLines":false,"confirmCheckDialog":false,"confirmRetryDialog":false,"acceptSpellingErrors":false},"scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","a11yCheckingModeHeader":"Checking mode","confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"questions":["
Referencing the brief history of Earth and the Geologic Time Scale, when did life first<\/strong> evolve? (Give answer with number first and unit for second part.)<\/em><\/p>\n\n
Number: *3.85\/3.8\/3.9* <\/p>\n\n
Unit (Ga or Ma or Ka): *Ga*<\/p>\n"]},"library":"H5P.Blanks 1.14","metadata":{"contentType":"Fill in the Blanks","license":"U","title":"Evolution of Life"},"subContentId":"772091d5-46b8-458b-bbef-c101e2dc9200"},{"params":{"media":{"disableImageZooming":false},"text":"
Fill in the missing words<\/p>\n","overallFeedback":[{"from":0,"to":100}],"showSolutions":"Show solution","tryAgain":"Retry","checkAnswer":"Check","submitAnswer":"Submit","notFilledOut":"Please fill in all blanks to view solution","answerIsCorrect":"':ans' is correct","answerIsWrong":"':ans' is wrong","answeredCorrectly":"Answered correctly","answeredIncorrectly":"Answered incorrectly","solutionLabel":"Correct answer:","inputLabel":"Blank input @num of @total","inputHasTipLabel":"Tip available","tipLabel":"Tip","behaviour":{"enableRetry":true,"enableSolutionsButton":false,"enableCheckButton":true,"autoCheck":false,"caseSensitive":true,"showSolutionsRequiresInput":true,"separateLines":false,"confirmCheckDialog":false,"confirmRetryDialog":false,"acceptSpellingErrors":false},"scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","a11yCheckingModeHeader":"Checking mode","confirmCheck":{"header":"Finish ?","body":"Are you sure you wish to finish ?","cancelLabel":"Cancel","confirmLabel":"Finish"},"confirmRetry":{"header":"Retry ?","body":"Are you sure you wish to retry ?","cancelLabel":"Cancel","confirmLabel":"Confirm"},"questions":["
Referencing the brief history of Earth and the Geologic Time Scale, when did life move onto land (plants were first!)<\/strong>? (Give answer with number first and unit for second part.)<\/em><\/p>\n\n
Number: *438*<\/p>\n\n
Unit (Ga or Ma or Ka): *Ma*<\/p>\n"]},"library":"H5P.Blanks 1.14","metadata":{"contentType":"Fill in the Blanks","license":"U","title":"Life moves onto land"},"subContentId":"9fb80ca9-ce85-4dc9-8aa8-86593374dcb4"},{"params":{"media":{"disableImageZooming":false},"taskDescription":"
Drag the events in Earth's history into the correct order.<\/p>\n","overallFeedback":[{"from":0,"to":100}],"checkAnswer":"Check","submitAnswer":"Submit","tryAgain":"Retry","showSolution":"Show solution","dropZoneIndex":"Drop Zone @index.","empty":"Drop Zone @index is empty.","contains":"Drop Zone @index contains draggable @draggable.","ariaDraggableIndex":"@index of @count draggables.","tipLabel":"Show tip","correctText":"Correct!","incorrectText":"Incorrect!","resetDropTitle":"Reset drop","resetDropDescription":"Are you sure you want to reset this drop zone?","grabbed":"Draggable is grabbed.","cancelledDragging":"Cancelled dragging.","correctAnswer":"Correct answer:","feedbackHeader":"Feedback","behaviour":{"enableRetry":true,"enableSolutionsButton":true,"enableCheckButton":true,"instantFeedback":false},"scoreBarLabel":"You got :num out of :total points","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yShowSolution":"Show the solution. The task will be marked with its correct solution.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","textField":"Place the following events from the earliest part of Earth's history into the order in which they occurred. (Start at bottom and work your way up)\n\n540 Ma: Most recent in this list: *Hard parts evolve*\n\n*Multicellular life evolves*\n\n*Eukaryotes evolve (nucleus)*\n\n*Photosynthesis first occurs*\n\n*Life evolves (prokaryotes)*\n\n*Oceans form*\n\n*Hard crust first forms*\n\n4.6 Ga: Most ancient (oldest): *Earth formed*"},"library":"H5P.DragText 1.10","metadata":{"contentType":"Drag the Words","license":"U","title":"Untitled Drag the Words"},"subContentId":"9a95fdf6-26eb-4f2d-9a70-6df0501d2085"},{"params":{"media":{"disableImageZooming":false},"taskDescription":"
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\n
Additional resources for deeper exploration or further clarification<\/strong><\/p>\n\n
\n
Textbook chapters<\/strong><\/p>\n\n
\n\tOpen Textbook: Physical Geology, by Steven Earle -- Geologic Time<\/a> <\/li>\n\t
Open Textbook: Introduction to Geology, SLCC -- Earth History<\/a><\/li>\n\t
Open Textbook: Vision Learning: Biology -- Origins of Life<\/a><\/li>\n\t
Open Textbook: LibreTexts: Microbiology -- Anoxygenic Photosynthetic Bacteria<\/a><\/li>\n<\/ul>\n\n
\n
Websites and VIdeos<\/strong><\/p>\n\n
\n\tLecture photo album: Earth History (Fossils and Other Evidence<\/a><\/li>\n\t
How do we date rocks? Tutorial: Radiometric Dating<\/a><\/li>\n\t
MIT News: Zeroing In on When Oxygenic Photosynthesis Evolved<\/a><\/li>\n\t
Website: Story of Time and Life<\/a><\/li>\n\t
13-minute video: NOVA PBS Origins of the Universe<\/a><\/li>\n\t
50-minute video: NOVA PBS How Life Began<\/a><\/li>\n\t
6-minute video: NOVA Stromatolites: World's Oldest LIving Fossil | Making North America<\/a><\/li>\n\t
Website interactive: Deep Time<\/a> -- Howard Hughes Medical Institute<\/li>\n\t
Website interactive: Geological History of Oxygen<\/a> -- Howard Hughes Medical Institute<\/li>\n\t
Sketchfab 3D model: Trilobite<\/a><\/li>\n\t
Caltech -- Video Lecture -- Claire Bucholz, 1\/19\/23, When Earth Breathed Deeply<\/a>.<\/li>\n\t
NOAA website tutorial: Chemosynthesis and Hydrothermal Vents<\/a><\/li>\n\t
National Park Service: The Stromatolites of Glacier National Park<\/a><\/li>\n\t
Website: Smithsonian Institution: Early Life on Earth -- Animal Origins<\/a><\/li>\n\t
Website: Cal Poly Humboldt: Natural History Museum -- Life Through Time Visual Timeline<\/a><\/li>\n\t
Website: Digital Atlas of Ancient Life<\/a><\/li>\n\t
Website: Paleobiology Database<\/a><\/li>\n<\/ul>\n"},"library":"H5P.AdvancedText 1.1","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"},"subContentId":"e121f981-9bd5-466a-a60e-1d728e02d156"},"useSeparator":"auto"}]},"library":"H5P.Column 1.18","subContentId":"7fbb2f3b-f328-4b53-adbf-4ac40773d099","metadata":{"contentType":"Column","license":"U","title":"Additional Resources"}}],"behaviour":{"defaultTableOfContents":true,"progressIndicators":true,"progressAuto":true,"displaySummary":false,"baseColor":"#1768c4","enableRetry":true},"read":"Read","displayTOC":"Display 'Table of contents'","hideTOC":"Hide 'Table of contents'","nextPage":"Next page","previousPage":"Previous page","chapterCompleted":"Page completed!","partCompleted":"@pages of @total completed","incompleteChapter":"Incomplete page","navigateToTop":"Navigate to the top","markAsFinished":"I have finished this page","fullscreen":"Fullscreen","exitFullscreen":"Exit fullscreen","bookProgressSubtext":"@count of @total pages","interactionsProgressSubtext":"@count of @total interactions","submitReport":"Submit Report","restartLabel":"Restart","summaryHeader":"Summary","allInteractions":"All interactions","unansweredInteractions":"Unanswered interactions","scoreText":"@score \/ @maxscore","leftOutOfTotalCompleted":"@left of @max interactions completed","noInteractions":"No interactions","score":"Score","summaryAndSubmit":"Summary & submit","noChapterInteractionBoldText":"You have not interacted with any pages.","noChapterInteractionText":"You have to interact with at least one page before you can see the summary.","yourAnswersAreSubmittedForReview":"Your answers are submitted for review!","bookProgress":"Book progress","interactionsProgress":"Interactions progress","totalScoreLabel":"Total score","a11y":{"progress":"Page @page of @total.","menu":"Toggle navigation menu"}}

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