Questions tagged [earth-history]

Questions relating to Historical Geology.

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5
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0answers
90 views

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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135 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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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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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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2answers
111 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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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 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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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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1answer
184 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
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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
215 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
96 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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144 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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279 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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1answer
76 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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214 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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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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3answers
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How did Earth's plate tectonics start?

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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4answers
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What was the first rock in the rock cycle?

I am an undergraduate student but I am a tutor at a High School, and one student asked me. Attempting to explain the rock cycle "if one rock turns into the other then which came first" my gut is ...
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206 views

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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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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1answer
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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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1answer
63 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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1answer
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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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1answer
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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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1answer
118 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 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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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
168 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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1k views

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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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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1answer
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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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177 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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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
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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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412 views

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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1answer
135 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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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 ...