Questions tagged [earth-history]

Questions relating to Historical Geology.

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2answers
133 views

Are we entering a new Ice Age according to Milankovitch cycles?

Milankovitch cycles consist of three orbital parameters: eccentricity, obliquity, and precession of equinoxes. According to Milutin Milankovitch, the most recent glacial period ended nearly 11,000 ...
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1answer
104 views

How much of the petroleum ever formed has made it into reservoire rocks?

I am aware that it's a bit general a question, and petroleum geology (or petrology ;-)) has never been a field of interest to me. A superficial search using related keywords brings up only economic ...
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What do scientists mean when they say the Earth formed 4.56 billion years ago? [duplicate]

Does that mean that the Earth gained the classification of a planet that long ago rather than some other celestial body? How did they determine that this happened that long ago? How discrete is the ...
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106 views

Geo-Spherical shape of Earth

I know that the best possible approximation of the shape of earth is an oblate sphere. But people also call it as geo-spherical shape of the Earth. What is the meaning of geospherical shape? Does this ...
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86 views

What were the Two Largest Forests of Western and Central Europe (circa 600 BC)

I am trying to find out what forests were the largest in Western and Central Europe, around 600 BC. I understand that accounts dating that far back may be difficult to find, but I hope other sciences ...
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Has a scientific consensus been reached concerning the formation of the Grand Canyon?

new student of Oceanography here! I'm studying Earth Science right now, and I found conflicting reporting re: the formation of the Grand Canyon; whether it was formed singularly by the Colorado ...
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2answers
138 views

How was the onset of the Cambrian period dated?

What dating method was used to determine the beginning of the Cambrian, and what was its margin of error? Was only one fossil dated, or were a number of similar fossils used?
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84 views

Earth-like conditions on Titan: is it feasible that Titan once had seas and lakes of liquid water?

Given that: 1) Four billion years ago Saturn was hotter and radiated strongly in the infra-red. . . . . . . . . . 2) Like Earth's moon, Titan was then closer to its planet. . . . . . . . . . 3) Like ...
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How many days has it been since the Cambrian explosion?

I want to know how to calculate the number of days since an event in Earth's past, and am using the Cambrian explosion as an example. I define a day to be one rotation of Earth with respect to the ...
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116 views

What has been the influence of the moon on Earth's temperature?

What proportion of Earth's internal heat is generated by tidal flexion as a result of the orbiting moon, and would it have been significantly greater four billion years ago when the moon was closer? ...
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146 views

How quickly is the Earth shrinking?

Except for ice, acetic acid, bismuth and gallium and a few other things materials generally shrink when they cool and solidify, so I'm pretty sure Earth has as well. It probably wouldn't be ...
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193 views

How long ago was the first limestone formed?

It is readily apparent from the fossil record that the first limestone was laid down hundreds of millions of years ago, but how long ago was the very first limestone formed? It could be approximately ...
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142 views

Is Earth inhospitable?

It's thought that, shortly after Earth was done being refurbished resurfaced during the Late Heavy Bombardment, life abio-generated almost as soon as it was able to. The short delay led to speculation ...
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193 views

Where did the continents come from?

In animations that show the location / drift of the continents over the aeons, it seems that the continents (or cratons?) are just floating / drifting around, sometimes fusing or splitting, but having ...
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2answers
88 views

Why are $\small\sf{CH_4}$ and $\small\sf{CO_2}$ levels coupled during the Pleistocene?

CH4 and CO2 levels show correlation throughout the Pleistocene: Source: trustyetverify.wordpress.com What are the reasons of this coupling?
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1answer
217 views

What Caused The Sea Levels to Drop During the Maastrichtian Epoch?

Anyone who has studied ice ages would know that during the last two-and-a-half million years of Earth's history, there have been periods where there was enough ice to suck up a lot of water. As a ...
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1answer
97 views

What were the geometric coordinates of the Chicxulub impactor 66 million years ago?

At the moment around mexico we can find the leftovers of the Chicxulub impactor which could have extincted most dinosaurs. But 66 million years ago was after the breakdown of Gondwana. So back to ...
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1answer
147 views

Has Earth's atmosphere lost mass throughout the geological ages due to biological $\small\sf{CO_2}$ fixation?

Stromatolites and other organisms have been storing $\small\sf{CO_2}$ in the form of $\small\sf{CaCO_3}$ throughout the geological ages, forming extensive limestone deposits scattered across Earth's ...
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1answer
320 views

Where did the atmosphere's nitrogen come from? [duplicate]

According to Wikipedia's article Atmosphere of Earth: Outgassing from volcanism, supplemented by gases produced during the late heavy bombardment of Earth by huge asteroids, produced [Earth's ...
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2answers
218 views

Original Diameter of Ancient Impact Craters [closed]

The 2.25 billion-year-old Yarrabubba crater in Western Australia has recently been identified as the world's oldest impact crater. It is said to be 43 miles (69 km) in diameter, yet the photo which ...
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129 views

Cratonization - how did the Archean cratons form?

Before the onset of modern style plate tectonics and the Wilson cycles in the late Archean, it is thought that smaller units of continental crust, called cratons, roamed the oceanic crust over a more ...
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1answer
80 views

Earth History Book

I'm a PhD student studying the (current) climate of the Earth. I'm also quite interested in the history of planet Earth, although I have little academic background in that area. Is there a good ...
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43 views

Are Iron Meteorites a Good Guide to the Composition of the Earth's Core?

Occasionally, very large nickel/iron meteorites strike the Earth, and on examination it is apparent that they were once part of a much larger body which had differentiated into a metallic core and ...
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With so many positive feedbacks accelerating global warming, how did the earth ever re-enter ice ages after it came out of one?

We hear a lot about positive feedbacks when it comes to global warming. For example: ice reflects solar radiation, so as the ice melts more solar radiation is absorbed which accelerates warming; ...
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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? [duplicate]

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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1answer
128 views

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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155 views

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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113 views

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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1answer
137 views

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 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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34 views

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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54 views

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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194 views

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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302 views

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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3answers
409 views

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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1answer
102 views

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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1answer
177 views

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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3k views

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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2k views

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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1answer
136 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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986 views

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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1answer
114 views

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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1answer
152 views

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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490 views

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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246 views

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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1answer
290 views

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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1answer
2k views

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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2answers
172 views

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?