Questions tagged [geology]

The science comprising the study of the rocks Earth is composed of, and the processes by which they change. Some subfields of geology are petrology, mineralogy, and geophysics.

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Possibility of naturally cut diamonds

Is there a chance that diamonds may naturally occur as any of the geometric shapes in such a way that it is naturally brilliant and cut? Obviously, I am not expecting really sophisticated cuts but ...
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hi, any ideas how to convert Rcd and Dst seismic data into SEGY?

any ideas how to convert Rcd and Dst seismic data into SEGY?
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How do these holes form?

I was casually browsing the google earth street view map today. And I noticed strange cavities in a rock wall on Henderson Island, a coral island in the South Pacific. What could have caused this to ...
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Does this support Hapgood's Earth Crust Displacement Theory?

I'm no Geologist by any standard but I'm quite intrigued by what goes on below our feet. I came across this article that states there's a new or (confirmed) partially melted layer in the athenosphere (...
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How does the caprock of aeolian landforms such as mesas, buttes and hoodoos protect the underlying soft rock?

Why do we see a bipartite cliff,i.e., a vertical top portion and a slanted bottom portion at the edge of a mesa or butte? I came to know from the internet that the top portion is the hard caprock And ...
3 votes
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The total pressure / total mass of earth's atmosphere on geological time scales

In many introductory geology courses, a great deal of time is spent on the historical composition of earth's atmosphere: the great oxygenation event, oxygen maximum during the carboniferous, ups and ...
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Round structure in southern United States

Assuming here might be someone who knows something about this, I wanted to ask what is behind this round structure I have spotted today on Google Earth: There seems to be a large (~200 km), nearly ...
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1 answer
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What causes "hydrocarbons" to take the form of petroleum versus natural gas?

"Hydrocarbons" are found in geological formations consisting of strata or layers of rocks. Specifically, they are formed from decomposed organic material (that contains carbon), that bonds with ...
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What rock layer is beneath the Vishnu Basement Rock in the Grand Canyon?

I read that the deepest part of the Grand Canyon that we can see are the Vishnu Basement Rocks, deposited 2 billion years ago (according to the Grand Canyon Wikipedia page). But what kind of rock lies ...
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1 answer
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Likely air composition in cave only accessible from underwater?

I recently stumbled on the images of the Cosquer cave, located in France, famous for being a comparatively recently discovered as a Paleolithic decorated cave. The entrance to cave now is more than ...
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Does the collision of India influence the geology and geography of some of the other mountains of Asia, or just the Himalayas and Tibet?

This here is a nice and lovely map of Asia. Note that the teardrop-shaped Tibetan Plateau dominates the map, and we have India to thank. For the last 50 million years, it has been pushing upwards, ...
13 votes
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How to determine how long ago a rock was broken?

I know that there are techniques that help scientists determine the age of a rock. But is it also possible to determine how long ago a rock was broken? For example, how could we date the formation of ...
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Is there a list of instances where mountains that have been mined out of existence?

Reading the Wikipedia entry for the Australian town of Broken Hill, I came across the following piece of trivia (emphasis mine): The "broken hill" that gave its name to Broken Hill actually ...
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Is it true that earthquakes are not felt in a cave?

I took a tour of a cave in northern California last weekend. The tour guide asked us, "If an earthquake occurred, what would we feel in here?" My answer was, "fear," but she said we would feel ...
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1 answer
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Stratigraphy of limestone applied to the Great Pyramid of Giza

The Great Pyramid of Giza is made from blocks of limestone quarried from the Giza plateau. The pyramid is composed up of about 200 layers, with individual blocks varying in thickness from 20 to 60 ...
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How is the difference in crust and mantle composition explained?

We know that the composition of the crust is SiAl and SiMa and the one of mantle is mostly ophiolites, but why? Which are the geological processes that make this difference exist?
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What happens to seismic waves reflected back to the surface?

What would be the behavior of seismic waves when it hit the geological media? The waves coming from a source hits different boundaries with different energies, the wave will be reduced in energy by ...
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At what depth does the underground begin to warm up?

Spring water comes out colder from being underground. But if you get deeper the temperature goes up. At what depth does the underground stop getting colder and begins getting warmer? Is there a map ...
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1 answer
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Why can't we dig deeper?

I recently read on another SE site that there's a limitation on how deep we can dig into the earth. A Google search reveals that temperature is the problem. I quote from a Popular Mechanics article, ...
5 votes
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Why does calcium occur together with felsic rocks and magnesium with mafic rocks if calcium is denser than magnesium?

Felsic rocks contain a lot of sodium, potassium and calcium (and a great deal of aluminum), while mafic rocks consist of a lot of magnesium with iron.... Why is this? Why is magnesium (z=12) in the ...
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How fast and big would the waves be in the rocks from the Richter scale 10 earthquake at Chixulub

If I was near Australia and China when the 10km meteorite hit Chixulub 65 million years ago, the first thing I would have noticed is an earthquake high above magnitude 9, and the ground would shake by ...
3 votes
1 answer
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Where can I find worldwide standards of manganese mining?

Hi everybody who sees this post, I need urgent help for finding all official world wide standards of the manganese mining. Problem is that, many houses has been damaged in my village with manganese ...
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How do geologists examine mountains and hills inwardly?

There is an idyllic verdant valley where I live, full of mountains and hills. Most mountains are covered by vegetation, but some have flat steppe-like tops where people have small farms and homesteads....
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1 answer
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What is the reason behind the density being negative value

This is the example density depth functions for various sedimentary sections world wide. But someof the sections marked with red, due to their last term, as i increase the value of z(depth) they ...
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What criteria determines whether earthquakes are classified as new or aftershocks?

I saw a recent paper where it is claimed that aftershocks can occur years, decades or centuries after the main earthquake. When seismic activity is observed, what criteria determines the ...
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Input of the relation, source and receptor files into SLB Omega

Is anyone using SLB Omega that knows how to input the source, relation and receptor files that are not using SPS format?
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1 answer
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Pre-Phanerozoic CO2 levels and pluricell life influence in C Earth's cycle

This graph presents an estimate of Phanerozoic CO2 levels on Earth. From the onset of the graph, it appears that CO2 levels are rising. However, I've come across papers, such as this one, suggesting ...
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1 answer
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Is there any correlation between La Niña/El Niño and seismic activity?

I've read in the past that extreme precipitation levels may have an effect on seismic activity, and wondered if anyone has ever analysed the La Niña / El Niño cycles to see if there is any correlation ...
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How to extend the Wyllie time average equation to multiple constituents

I understand the Wyllie time average equation How to extend it to multiple constituents ?
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Good modern paper demonstrating differentiation of glauconite and berthierine using xrd or FTIR

I'm looking for a recent paper that demonstrates how one would unambiguously differentiate glauconite from berthierine and have yet to find something useful. I'm running across a lot of papers seeming ...
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Is the Pacific Plate composed of smaller plates?

The question, Why are all lower mantle plumes under oceans? has the following diagram which was taken from Wikipedia Commons. About half of the large red dots occur on or near the boundaries of ...
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How to compare sensitivity with lithology between different crossplots?

In the given figure, which is plot of various elastic parameter for sand (blue) and shale(red) sequence. How to find Which crossplot has has greater sensitivity to lithology? Also what is mean by ...
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Why is static modulus greater then dynamic modulus in limestone?

Generally dynamic modulus is greater then static modulus and experimental data matches that. But in chalcedonic limestone, the static modulus looks to be greater than the dynamic modulus. What could ...
3 votes
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What is the reason that some elastic constants are negative?

In this table of elastic constants, indices m = 1 and n = 4 result in negative values. What could the reason be?
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How much of the planet's land mass is between the Tropic of Cancer and Tropic of Capricorn [closed]

I know this isn't readily available. I know that it is 68% Northern Hemisphere vs 32% Southern. And I know that it's 68% Eastern vs 32% Western. My wife asked me why I wanted to know and she got the ...
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Why the groundwater depth is different in same area

I recently measured groundwater levels using a tape in three different boreholes for where the holes are in same area. Each hole had a different level of water. Holes A and B are just 4 meters apart ...
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1 answer
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Why are all lower mantle plumes under oceans?

Having a look at the attached image (original at Wikipedia Hot Spot page) I noticed that all mantle plumes originating from lower mantle (in red) are under oceans. Why?
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what is the value of y in additive time series decomposition

I understand the additive time series formula is y = trend + Seasonal + cyclic + residual. But what is the value of y. Is it the the combination of trend, seasonal , cyclic and residual which is shown ...
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How to connect drillhole from section to the planar view to calculate dip and azimuth?

We have a set of old sections with drill data that I would like to extract and model. I can add sections just fine in Leapfrog, but I have issues with the drill holes, especially connecting the drill ...
3 votes
1 answer
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What is this long mark undersea

Visiting Google Maps, I came across this long, sinuous, while pretty regular mark undersea that looks like an ancient river, when the sea was way lower, or a big (big!) boulder that could have rolled ...
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Estimation of rare earth elements in the SUAC complex

I am currently competing in a case study competition a part of which has asked us to estimate the amount of Nd, Pr, and Dy in the SUAC complex (Sung Valley Ultramafic-Alkaline-Carbonatite) in electric ...
8 votes
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What determines when the end of a volcanic eruption will happen?

The Cumbre Vieja volcano of La Palma Island, Spain, started to erupt 3 months ago. This week, the volcano stopped emitting lava and there remains only degassing processes. According to this news story,...
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From how deep in the mantle has any rock ever been brought to the surface? Have scientists found anything they believe originated in the outer core?

I wonder if this is even possible to know.... Do geophysicists and geologists have even a 'theoretical' idea about how deep Earth's churning of its layers goes?
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How is the apparent volume affected by particle packing?

This is from paper "The packing of particles" by A.E.R Westman and H.R. Hugill. Here they give result as, "it is evident that if the diameter ratio is unity, ie., the coarse and fine ...
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How accurate is the law of superposition?

Recently I started being more interested in the rational details of the sciences (... being often challenged about them by a creationist friend) and one of the creationist 'theories' I've encountered ...
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Do subducted continents rise up again through ridges?

Layman here, sorry if this is a stupid question. I have a geology friend who recently told me that plate tectonics is like how warm milk cools on top to form thin solid layers. The convection cells in ...
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Are These Leaf Fossils Found Near a Texas Lake Shore?

I recently came across some intriguing specimens near a lake shore in Texas and am seeking your expertise to help identify them. The objects have a few characteristics that lead me to believe they ...
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What forces plays the role in order to subduct the denser tectonic plate under the lighter plate?

I am a 10th grade student and I don't know much about geology but I'm learning about subduction online. It's always mentioned that the denser plate gets subducted under the lesser denser plate. I want ...
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Can a braided stream create thick relatively continuous siltstone beds?

I am attempting to interpret an outcrop I went to. I suggested it was created by a braided stream. The one thing I cannot explain are prominent alternating siltstone and sandstone beds. There are ...
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What is the geologic origin of the Bauxite deposit in Bauxite, Arkansas, and could there be more?

Bauxite is an mineral of Aluminum. Despite a general mineral wealth, the USA does not have any major Bauxite deposits, except for one in Arkansas. The mining town was named Bauxite, Arkansas. The ...

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