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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Height of Everest from base to top

It's relatively well known that Everest is the highest mountain above sea level, and that Mauna Kea in Hawaii is the tallest mountain from base to top. But how tall is Everest from base to top? Or to ...
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Why was the temperature change greater in higher latitudes than in lower latitudes during the Paleocene/Eocene thermal maximum?

In the "Plankton cooled a greenhouse", which is the article written by Birger Schmitz, it is stated that the subtropical regions became warmer during the PETM(Paleocene/Eocene Thermal Maximum) but the ...
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Information on this rock, and identity? [closed]

My aunt gave me this rock. She has had for years. She was given it by a relative who passed many years ago. She said it was called a Tuffy (not sure which way it should be spelled) and that it came ...
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Calculate normal and shear stresses with fault plane dimensions, slip, orientation and regional stress tensor

I'm trying to verify that some code I have is running correctly when calculating the Coulomb stress change. So for a example I have a fault with : Length = 70 m, Slip= 0.004 m, Orientation(strike/dip/...
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How did this hole / hollow form within this rock?

Can you assist me in understanding how this hollow was formed in this rock. I am told that it has to do with cementation but I believe that geological process produces rounded canonball ( sometimes ) ...
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Could someone tell me what this stone might be [closed]

It is 9 1/2 inches by 3 1/2 inches and weighs about 5 lbs. it was at this house in Florida when we bought it. It has a white 1/4 inch crust and the interior color looks somewhat topaz.
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where are the poles of rotation of the tectonic plates located?

Euler's "fixed point" theorem ... can be stated as: The most general displacement of a rigid body over the surface of a sphere can be regarded as a rotation about a suitable axis which passes ...
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What Makes Round Holes In Superior Agates? [closed]

I found this rock in Western Wisconsin. Pretty sure it's a Lake Superior Agate? Wondering what would make the white eye that has red in its center? Would this rock be a good one to have someone cut ...
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Marks on boulders of volcanic origin

I am working in a catchment in the southern Ecuadorian Andes, about 3700 m.a.sl. Rock outcrops at the upper part of the catchment, as massive blocks varying their size from one meter up to five meters,...
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If two adjacent tectonic plates are moving in the same direction, is there significant interaction at the boundary?

If two adjacent tectonic plates are moving in the same direction, is there significant interaction at the boundary? Is it just a convergent boundary if one moves faster and "catches up" with the other?...
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Can an igneous rock have a Vp of less than 1000 m/s and need blasting to excavate?

I have run a 60 m refraction seismic line on a mountain summit. The environment was noisy (wind would be the principal agent) and quite difficult to pick first arrivals. It resulted in 800 m/s. A ...
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Is there any possible future for high energy geophysics? If so how it is going to revolutionize our knowledge about Earth's interior?

How practice is to map/image the subsurface of the earth using the high energy particles like neutrinos? https://www.geosci-instrum-method-data-syst.net/special_issue2.html
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Can living where magnets are abundant provide a mini-magnetoshere?

Are there a mini-magnetosphere within the magnetosphere similar to mini-magnetosphere found on the Moon? Is there a map of these areas that would resemble the white swirls in the picture below? The ...
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What is the History of the Brooks Range?

This here is a map of the Brooks Range in northern Alaska: As you can see, it is an inland range shaped in a downward curve. Why is that? What is the history of the uplift of the Brooks Range? How ...
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"Obicular" structures in basalts

I found spherical or globular structures, structures in basalts of a greenstone belt which underwent alteration and deformation. However, in thin section, these structures have undeformed pyroxene and ...
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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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Should I perform EOF analysis on an unevenly-spaced time series?

I have a dataset of sample concentrations of several ions/elements (Ca 2+, SO4 2-, K +, S, Ca, V, etc.) from an ice core which I am using to detect volcanic eruptions. The raw version of the dataset ...
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Is there limestone under the Oregon Coast Range?

I've found some diagrams of the Oregon Coast Range, but they are very basic. An friend said he thinks there is limestone deep underground, but my understanding of the formation of these mountains is ...
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Are sand deserts the greatest natural convection heaters on Earth?

Ask any climate scientist the question: "Why are deserts so hot in the day time and so cold at night" and generally you will get the same answer, it’s all about the lack of moisture and latent heat ...
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How Can We Establish Precisely What Earth's Core is Made Of?

The consensus view is that that the Earths core is composed mainly of iron alloyed with about 10 percent nickel and traces of other heavy metals, but I have seen at least one account which says it is ...
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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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How older is this snail shell possible could be?

Last weekend I was in Xınalıq(the village in Azerbaijan) and found this snail shell. I am wondering how old is this?
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Climate consequences of very large asteroids striking the Deep Ocean

For every asteroid or meteorite that hits dry land, two hit the sea. If a Manicouagan-sized asteroid struck the deep ocean (but not above a trench),how would the H2O vapour, chlorine, iodine bromine ...
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7 votes
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Could the Grand Canyon be flooded by the ocean if it got deep enough?

The Colorado River has been carving the Grand Canyon for a few million years now, such that the canyon floor is around 6000 feet lower in elevation than the surrounding area, at about 2400 feet above ...
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Peninsula vs Cape [closed]

I know that Peninsula is much larger than a cape, but is there a definite way to differentiate them? I.e. by area- if the total area is larger than 30 sqkm, any headland is classified as peninsula..
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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 ...
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3 answers
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Is there a widely accepted reason for the formation of tafoni?

Expansion of tafoni seems to be based on weathering (seems reasonable enough.) But what creates them in the first place? There are a number of explanations online (Wikipedia lists eight plausible ...
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5 votes
1 answer
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Is sterescope still used to do cartography with orthophotography?

I used this tool at my degree a couple of lusters ago to do cartography with aerial orthophotos. We used it on cartography and geomorphology subjets. Source: gumtree.com The method consists ...
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Is this a geode? [closed]

So just having issues with identification looks like a outer line of rock a bit transparent but the inside polished looks waxy other side of stone a bit more foggy but still blue visible Edit - ...
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5 votes
3 answers
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If the Kola Superdeep Borehole were opened today, what would come out of it?

The BBC News article The Deepest Hole we have Ever dug says: This is the Kola Superdeep Borehole, the deepest man made hole on Earth and deepest artificial point on Earth. The 40,230ft-deep (12.2km) ...
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How much hydrogen can be extracted from the deep continental crust?

Far below the earth's surface, hydrogen gas is continuously produced through serpentinization. At least some fraction of this hydrogen remains trapped in the deep continental crust; indeed, Soviet ...
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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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could a rhyolitic magma melt a ferromagnesian mineral like olivine?

if the temperature of a felsic magma is about 800-650 °C and olivine melting point oscillates between end members forsterite and fayalite near 1900-1200 °C, Does this mean that an olivine crystal in ...
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3 votes
1 answer
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Why doesn't Earth absorb our carbon emissions?

If we look at the carbon cycle, we see that man-made carbon emission only account for a tiny fraction of all $\text{CO}_2$ emissions. However, we see a steady rise in atmospheric $\text{CO}_2$-levels....
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Is there a name for subduction boundaries at the North of Australia?

I know the ridge at the South of Australia is named Southeast Indian Ridge. I would like to know if there is a geological name for the three subduction branches that cross indonesian zone, at the ...
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What are the farthest Time Zone locations? [closed]

What place in the world has the farthest time zone? I heard it was Kiribati but then I found that Apia (Samoa) is further. So, is there anyplace that is the farthest in time than these two? What about ...
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How can I identify "tough" (mixed) granites?

I am trying to parse an old geologic description of stone suitable for use as road metal: Care must be taken to distinguish the difference between the hardness of a stone and its toughness......
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Can gemstones be cut into sheets? [closed]

TL;DR: Without lasers, electricity, or otherwise modern tools, could large transparent gems be sliced (like glass window)? So I’m world building. On this planet they have caves with enormous gemstone/...
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What is the basis for the Geologic Time Scale

The Geologic time scale was completed in the mid to late 1800s. What methods were used to date the various subdivisions?
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3 answers
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how can a asterisk/star like crack occur on a rock?

how can a asterisk/star like crack occur on a hard pyroclastic rock? Could it caused by a meteroite or by some other mechanism? You may see the shape of the rock on attached photo.
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2 votes
1 answer
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An oblique-square-prism crystal?

Does any mineral crystallize in the shape of an oblique square prism? If so, what crystal system (monoclinic, cubic, hexagonal, etc.) would such a mineral fall under?
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Did low $\small\sf{CO_2}$ levels affected Permo-Triassic mass extinction?

After answering this question: How did plants adapt to $\small\sf{CO_2}$ levels past 400k years? Why won't they do it again? I know Permo-Triassic mass extinction is associated to a catastrophic ...
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How big were the Siberian Traps originally?

252 million years ago, Siberia was subject to a mass series of flood basalt eruptions, creating a large igneous province called the Siberian Traps. Today, it measures three million square miles (7.77 ...
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1 vote
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What is an isolated land area of one type of rock surrounded by land of a differing rock type called?

For example, if there were a large land area with exposed basalt, in the middle of which is a smaller isolated patch of Granite, what is that isolated patch called? I came across the single-word ...
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Identification of limestone type

These are images of a stone found and used extensively in the Jammu & Kashmir region between India and Pakistan. These are called devir or devri in the local parlance. Following is the ...
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14 votes
3 answers
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Would oceans regenerate if removed?

On Earth, there is enough Hydrogen and Oxygen to make 13,88 million km$^3$ of water (calculation below). However, oceans contain only a tenth of that. Clearly, most of the hydrogen must be stored in ...
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Are we at the beginning of a Heinrich Event?

Does our current weather trend properly reflect a Heinrich Event? It seems like the drastic weather swings are what I would expect but I realize that is not definitive. I don't see the term bandied ...
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3 votes
1 answer
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What kind of lava tube feature is Cleopatra's Grave?

Cleopatra's Grave is a natural feature inside (warning: PDF) Catacombs Cave in Lava Beds National Monument near Modoc, California. Source: LookBeforeYouLive My apologies, as this image is somehow in ...
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What is the difference between subvolcanic rocks and plutonic rocks?

I'm studying Plutonic (Intrusive) rocks and I really don't understand the difference between Plutonic Rocks that form in Sills and Dikes from the so called subvolcanic rocks, also known as a ...
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How do you tell if smoky quartz has been irradiated?

I want to purchase a piece of smoky quartz crystal, but am not sure if it is irradiated. Is there a way to tell if it has been irradiated? Thank you.
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