Questions tagged [earth-history]

Questions relating to Historical Geology.

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26 views

How can radiometric dating of meteorites determine the age of the earth? Wouldn't this only determine the age of the decaying nuclide in each rock?

How can the radiometric dating of different meteorites determine the age of the earth? Wouldn't radioactive decay have already been occurring in all of those meteorites long before they hit earth? ...
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Can someone provide a map of Nazca lines with this image in it?

I found this image of a bird with another image below its right wing on google earth in nazca peru. Is there any maps or infomation available that can help me identify this one? Kind regards Jeff B.
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Why is Earth's inner core made of an iron-nickel alloy?

This question has puzzled me for a while. I know that earth's mantle is made of different minerals, metals and rocks etc. and that has always made complete sense to me. But why is the inner core made ...
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How Good is The Evidence For Snowball Earth?

Some geologists say there were times between 770 million years BP and 630 million years BP when ice ages were so profound that the Arctic and Antarctic ice caps met at the equator. This is called the ...
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Do earthquakes produce folds on rocks?

Earth rocks are frequently folded at surface. Folds in alternating layers of limestone and chert in Crete, Greece. Source: commons.wikimedia Are earthquakes the main mechanism ...
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Molten salt seas on the future Earth

As the sun gets brighter, the oceans are expected to evaporate by the next billion years or so (the vapor slowly gets stripped off into space). The salt, which is less dense than most rocks, will be ...
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What is the origin of the dominant atmospheric nitrogen content in Earth's atmosphere?

Comparing the atmospheric compositions of Earth with our nearest neighbours: As the table shows, the Earth's atmospheric nitrogen concentration is 78%, compared to 3.8% for Venus and 2.7% for Mars ...
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How old is the Earth?

According to most articles I've read online, the estimated age of Earth is 4.5 billion years. Question: How old is the Earth? So I actually want to confirm that this is the case. Maybe there are ...
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How did tectonic plates originally come to form?

Plate tectonics is a theory which describes Earth's lithosphere as being composed of distinct plates which are able to move atop of the underlying asthenosphere. At plate boundaries, this movement ...
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Which ocean is going to be swallowed by the Supercontinent Cycle, Atlantic or Pacific?

The register shows several supercontinents have been formed on Earth's History: "The most recent supercontinent, Pangaea, formed about 300 million years ago (0.3 Ga). There are two different ...
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Why is Earth's age given by dating meteorites rather than its own rocks?

Reading a course on Precambrian, I read that: Earth Age (around 4.5 billion years) is dated thanks to the meteorites hitting Earth during its formation rather than the inner materials composing the ...
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What is the fastest the Earth has ever spun?

How fast can the Earth rotate and support life? In prehistoric times, dinosaurs were so massive that archeologists wonder how they were not crushed under their own weight. Could a faster spinning ...
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Why is the bedrock buried so deeply in much of northern Minnesota?

Although parts of northern Minnesota have bedrock exposed at the surface (especially in the Boundary Waters area and along the short of Lake Superior), the more usual situation here is for the bedrock ...
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1950's - 60's Earth Science

I'm writing some lore for a fictional world, which is set in the 50's early 60's roughly. One thing I'd like to bring is a fairly grounded explanation for the creation of the planet and the universe, ...
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Age of the Earth without radiometric dating?

It is common knowledge that age of the Earth is roughly 4.5 billion years. Radiometric dating of meteorites (which were formed during the formation of Earth) and earliest rocks on Earth have both ...
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1answer
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What was the percentage of land mass in prehistoric times when temperatures were high enough that we had no ice caps?

I grew curious after watching a presentation about the large creatures of prehistoric times. One of the theories cited about why creatures were so big was the increased oxygen in the atmosphere due to ...
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Historically, how has the fraction of Earth covered by water changed?

Today, 70.8% of the Earth is covered in water (± a few tenths of a percent depending on how you account for lakes).1 How has this figure changed over the history of the Earth, and why? Of course, if ...
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How much does ocean cover percentage change between glacial periods? [duplicate]

Currently, oceans cover about 71% of the total area of Earth. Ice ages can cause this figure to fluctuate, by lowering the sea level and creating land bridges and other features. How much can this ...
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Has biology's influence in CO2/Phanerozoic variations been decisive?

I must say I always as geologist have explained myself CO2 changes at Earth's History in terms of Wilson Cycle. And I always thought biosphere is adapted to geology. But from two questions I link at ...
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During the “Ice Ages” or “Snowball Earth” times, where was all the energy?

We often seem to accept the idea that there were periods of time in which the entire surface of Earth was frozen, for the most part. This implies that there were periods of time in which the entire ...
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For what percentage of the earth's history has there been permanent ice?

Wikipedia comments here that "Permanent ice is actually a rare phenomenon in the history of the Earth, occurring only during the 20% of the time that the planet is under an icehouse effect." A "...
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Biomes that existed during the Paleocene-Eocene Thermal Max (PETM)

I understand that you could fill multiple books with descriptions of the PETM and the mechanisms that incited the event. I have always wondered what regions of the world were covered in what types of ...
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Where did the heiltsuk's find obsidian?

The discovery of hearths and other carbon dated items on an island off the north east coast of Canada puts modern humans there 2,000 years before the Alaskan land bridge existed. The glaciers of ...
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How much climate history can be reconstructed using marine sediment cores?

Today I learnt in college that marine sediments can be used to reconstruct the climate up to 500 million years back. I find that number very strange because in another class we learnt that the ocean ...
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Why is a future increase in solar luminosity by 10% supposed to have disastrous consequences for life on earth when the last 30% did not?

One remarkable thing about the climate history of earth is that despite the fact that solar luminosity was fully 30% lower in the beginning, temperatures were actually quite close to today. Since then ...
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Why Do Supercontinents Form? [duplicate]

It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future. ...
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Did an impact crater cause the formation of the gas fields in north eastern South Australia

In the paper High Impact Reservoirs, the authors claim that impact craters have lead to both the creation and destruction of petroleum source rocks, reservoirs and traps. Recently it was announced ...
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Have there ever been any islands that disappeared due to rising sea level?

With global warming comes rising sea levels. This has been going on for at least fifty years. So haven't there been some islands that have been swallowed by now? An island could be nothing more than ...
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134 views

Ocean water coming from Mantle vs coming from meteorites

Posibly duplicate from Water on Mars and Earth I remember well a hydrology course where our teacher made some calculations of the total flux of water from Mantle ejections in Earth's history. He ...
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Could the original H. naledi “burial chamber” have originally been at a shallower depth?

Homo naledi was a hominid that has recently made the news, in part because the discovery of a large number of fossils appears to suggest ritual "burials" by a species from 2.5 million years ago, ...
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Historically, how did the total amount of salt / NaCl on Earth develop?

After reading this question about the origin of NaCl on Earth, I'm wondering: How did the amount of NaCl develop historically? Is it a more or less linear growth until today? Was it such a linear ...
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Pangaea - Why did all the land mass form in one area?

The thing I find most interesting about Pangaea is that, if all the landmasses were connected, it leaves a massive amount of uninterrupted ocean everywhere else. It seems to suggest that there is a ...
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Have meteorites been found in the oldest sedimentary rocks?

Dropstones sometimes occur in sedimentary rocks. These are foreign rocks and boulders that happened to "drop" into a sediment and were fossilised when the sediment was lithified. (source: Michael C. ...
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Could the earth be much older than the currently accepted number?

According to wikipedia, the Earth is about 4.543 billion years old. If I understand correctly, this number is based on radiometric age-dating of meteorites. So basically, the logic is this: We've got ...
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When did wildfires start to occur on earth?

An oxidizer, fuel, and heat are needed for a fire. When considering oxygen as the oxidizer, an oxygen concentration of approximately 16% is required for combustion. Plant material is the fuel ...
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Causes of fluctuations in atmospheric oxygen in past 300 Mya

I have two questions based on the history of atmospheric oxygen levels depicted below. Source: https://commons.wikimedia.org/wiki/File:Sauerstoffgehalt-1000mj2.png. The notes below the chart explain ...
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Mass contribution during the LHB

How much mass (either absolute or relative to the Earth) was [estimate to have been] added to the Earth during the Late Heavy Bombardment?
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How many times in total has Earth formed a super continent?

I know there was a Pangaea at one point in history that broke into the continents of today, but I could have sworn there was another instance in Earth's history that there was a super continent, maybe ...
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Before the Great Oxygenation Event, where was the oxygen?

Today, the oxygen in the atmosphere is about 1018 kg. The estimated carbon biomass of the earth is about 4×1015. Less than 0.5%. Estimated fossil fuels are around 5 times as much as existing carbon ...
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Where did the carbon, neon and nitrogen go?

It is interesting to compare estimated Earth abundances with estimated Milky way abundances. Obviously the hydrogen and helium were gaseous and too light for Earth's gravitational field (other than ...
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Earth and moon have different mantle compositions. Is this a fatal flaw in the 'Giant Impact hypothesis'?

Deep impact ejecta on the moon seem to indicate that the moon's mantle is predominantly 'low-calcium pyroxene' (recent letter to Nature), whereas the Earth's mantle (or at least the upper mantle) is ...
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What would it be like to live in an ice age?

If you were born in the most recent ice age, how different would your life be compared to how you live it today? Furthermore, if humans currently lived in an ice age, how would it affect life today?
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If Earth had rings would gravity exerted by Earth decrease?

If Earth had enough mass in its own rings, more than the weight of Earth: What could it decrease the gravity to? Would the atmosphere have more depth or be thinner? What would the weather be like? ...
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How much heat flow is needed to maintain plate tectonics?

The Earth is emitting about 47 terawatts of heat energy, producing a heat flow of 0.0921 W/m$^2$ due to radiogenic and primordial heat energy. The heat flow drives mantle convection which in turn ...
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Why silicon is abundant in earth surface?

What is the reason for having silicon in so large quantity on earth surface?
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Water on Mars and Earth

If water on Earth came from meteorites, why doesn't Mars have substantial water? What made it more highly probable on Earth than on Mars?
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Why is Earth's Core Iron?

The two major constituents of the Earth's core are iron and nickel. In documentaries and scientific conversations, iron gets more attention than nickel, probably because it makes up a bigger ...
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Puzzle using relative dating principles

This isn't directly looking at a real life ecological example kind of thing, but it requires knowledge of relative dating, so I thought I would come here. Here is what was told: -"Worms" (curved ...
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Earth's orbit and historical sun-earth distance

Purpose of my question: I create program to calculate solar radiation and I need to calculate radius between sun and earth. The based on book "Guide to HTML, JavaScript and PHP" For Scientists and ...
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What is a “tar shower?”

I'm reading about Sodom and Gomorrah on Wikipedia when I come across this: "One such idea is that the Dead Sea was devastated by an earthquake between 2100 and 1900 BCE. This might have unleashed ...