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Questions tagged [earth-history]

Questions relating to Historical Geology.

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8
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4answers
462 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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1answer
129 views

How to measure the cycles of earth moving/rotation?

My knowledge of science is very basic, but after some research I have some knowledge, but I am still not clear with so many things regarding to this earth. I have read Laser's Measure the Earth's ...
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1answer
149 views

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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235 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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1k views

Life on Earth previous to us

I've seen in several places that there seems to be an extinction cycle on Earth of approximately 27 million years. I've read this here: http://www.dailymail.co.uk/sciencetech/article-1294372/Life-...
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1answer
803 views

Is a billion years of Earth's history missing?

Appears that a 4.4 billion-year-old crystal is oldest piece of Earth, and the crystal's chemistry -- specifically, the ratio of oxygen isotopes within it -- suggests that the temperatures on Earth 4.4 ...
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1answer
345 views

A circle shape in Madagascar

I was seeing Madagascar on Google Maps and accidentally i saw a circle shape near Bebao. Coordinates are 17.4317443°E and 44.644248°S. Please, to satisfy my curiosity, can you tell me why is this ...
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325 views

Historical atmospheric partial pressure & Henry's law constant

The explanation given for the fact that temperature has historically led CO₂ levels is Henry's law. Figure 1: Vostok ice core records for carbon dioxide concentration (Petit 2000) and temperature ...
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2answers
392 views

What fraction of Earth's crustal material survives the supercontinent cycle?

I know that things are not as simple, but for the sake of argument I'll assume a supercontinent cycle of $\sim$400 Myr periodicity is active on Earth. If that is the case, then my naive ...
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1answer
116 views

Who originated Taylor's axiom of lunar formation, and where?

I've been doing a bit of reading about the formation of the moon, and I've found multiple references (1, 2, 3) to something called Taylor's axiom, stated in link (3) above as: The best models for ...
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65 views

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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3answers
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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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2answers
400 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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2answers
637 views

What was the likely composition of Earth's early crust (how did crustal composition evolve)?

Was the first crust entirely mafic (oceanic) crust which was later distilled via volcanic arcs along subduction zones to make felsic rocks or did the earth start with bits of felsic crust? Are the ...
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1answer
502 views

How was the Earth formed?

What events took place in our Solar System which led to formation of the Earth? I have heard from sources that a big giant star exploded and the Earth was formed. Is this true ?
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99 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 ...
6
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1answer
155 views

How did the intensity of Earth's magnetic field change through geological time?

Looking at the wikipedia article on the Earth's magnetic field, I see that its strength varies through time. How did Earth's magnetic field change throughout its history, from the beginning of the ...
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1answer
578 views

The age of tectonic plates

There is information which says that East European Platform sticks out at the Baltic Sea and, therefore, we can see the ordovican layer in Estonia whereas ...
6
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1answer
196 views

What caused the earth's climate to stabilise ~10 thousand years ago?

We can see that the last glacial period ended 12-10K years ago. Interestingly enough, this also appears to coincide with the rise of large human civilisations. My question is: What caused the earth'...
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198 views

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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99 views

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 ...
5
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1answer
189 views

If we assume the mega impact hypothesis for the formation of Moon, where on Earth is the impact point?

Given that Pangaea had C-shape can we assume that the point of impact was in the center of this C-shape? In modern world it would be under Tibet? Or should we assume the oldest shape of the ...
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3answers
11k views

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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2answers
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Are there more earthquakes near the equator or poles?

When comparing the average distance of the all known earthquake epicenters to the nearest pole, is the longitudinal distance to the equator or the poles the smallest of the two? Please note that any ...
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2answers
110 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
524 views

What is the earliest tropical cyclone in record?

The question is simple: what is the earliest tropical cyclone (hurricane or typhoon) described in the historical record?
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2answers
635 views

Have the landmasses of North and South America ever been part of the same continent?

I know this question have been asked very often, but I could not find a proper answer around StackExchange, so I thought this might be a good place to ask: Have the landmasses of North and South ...
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2answers
167 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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2answers
621 views

Were all of Earth's minerals created before Earth's formation, during, or after?

I've heard that during the accretion of proto-planets that formed the earth, 60 minerals were created through the reactions of atoms and molecules in the nebula. Do these first minerals still make up ...
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1answer
141 views

Why haven't weeds overtaken the entire planet?

Given how rapidly weed plants spread and grow, choking out all other plant life, how come after millions of years we haven't ended with forests full of thistle or pokeweed, as opposed to pines or oak ...
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41 views

Distribution of thermometric devices on earth

In complex climate models, measurements of Earth-based thermometers are used. What is their geographic distribution - historically? Does each measurement get equal weight?
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1answer
132 views

Difference between the oxygen/$CO_2$ ratio during the period of the dinosaurs and the present

Here's the base of my question: Was volcanic activity more prevalent when the dinosaurs roamed? Is it true that during the time of the dinosaurs, both the oxygen requirements (by all living creatures ...
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2answers
117 views

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 ...
4
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1answer
735 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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1answer
237 views

Surface temperature in early hadean period

I am considering earth's internal heat budget for a project in university. For this I need an estimate on the temperature of the earth shortly after it had formed. In Kelvin's On the Secular cooling ...
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1answer
102 views

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 ...
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31 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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0answers
145 views

Did Theia collide directly with proto-Earth?

I was learning about the formation of Earth on Kahn Academy where it was mentioned that a protoplanet named Theia had a glancing impact with the earth and formed the moon. It seems like there is also ...
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2answers
354 views

Is this scientific explanation of The Bible flood accurate?

I googled "the flood and freshwater fish" and came up with this question Christianity StackExchange: How did Noah preserve fresh water fish?. The writer makes a lot of claims like how the salinity of ...
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1answer
156 views

Is there any place on Earth that is permanently a desert?

I am interested to know if there is any place on Earth that is permanently a desert (except Antarctica). By permanent I do not mean to be the physical meaning of forever. It means the place has to be ...
3
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1answer
224 views

Why is Great Oxidation Event associated with Iron oxidation but not Aluminum or Silicon?

Just to build up on my previous success with oxygen origin in the atmosphere, I want to expand the question as was advised in the answers. The official heresy, despite denied in the comments and ...
3
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1answer
226 views

How does water still exist on the Earth?

Almost all the theories that explain the origin of Earth says, it was way hot back then. That means It was in a lava state in its early days. Then gradually cooled down to the current state. If ...
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1answer
599 views

How much energy released by the Theia-Gaia impact?

I read somewhere that the Chicxulub impact released the energy equivalent of anywhere from 100-300 teratons of TNT. That's an impressive amount of energy. Assuming a head on collision (according to ...
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1answer
113 views

Future super-continent

What will the earth look like when the continents recollide? What will the climate be like? Assume global warming has been taken care of.
3
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1answer
133 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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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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1answer
246 views

Why do we see the limestone on top of Cambrian layer?

The official story says like Cambrian Ordovician transition was caused/accompanied by animals learned how to build the Ca-based skeletons. These skeletons and shells started to fall upon the sea bed ...
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0answers
80 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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40 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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0answers
32 views

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 ...