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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1answer
189 views

What are the cubic formations found inside Larimar gemstones?

I recently noticed what appears to be common cubic formations just beneath the surface of Pectolite (Larimar) gemstones. They quite resemble transparent sugar sprinkles. Each formation isn't perfectly ...
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Volcanoes in the Alps and Himalayas and the subduction of Tethys Sea

Geologist have theorized that the Tethys Sea subducted under Eurasian plates. But where are the volcanoes that would have resulted due to this? Where are the volcanoes in the Alps and the Himalayas?
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Can a shock wave travel around the Earth's curvature?

Can an explosion be felt in the ground on the opposite side of the Earth like from an asteroid? Would planes in the air on that side of the Earth be able to survive? Does the shock waive follow the ...
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Which Earth minerals would Moon colonists miss the most?

In my science-based novel, Moon colonists need to return to Earth to collect some rare or absent mineral(s) Ideally, something they could derive from seawater. Which minerals might they be...?
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What are the differences between alluvial, eluvial and colluvial deposits? [duplicate]

There's always confusion and disagreement when these terms are mentioned. Need to be sure of their exact meanings.
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What gravitational evidence do we have to counter the idea that oceans are formed when continents sink?

Is there some evidence for this based on gravity anomalies? I think I know how to tell if a mountain or structure is compensated based on bougeur and free air anomalies, but this really has me ...
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1answer
498 views

What structures form due to the melting of subducting plates? [closed]

What structures form from the melting of subducting plates? Plutons, Accretionary wedges, Deep sea trenches, Faults?
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1answer
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Which type of convergent boundary creates the tallest mountains? [closed]

Which type of convergent boundary creates the tallest mountains? Continental-Continental Ocean-Ocean Ocean-Continental
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830 views

What equation should I use in this isostasy problem?

I have this problem, and I am not sure where to start. The only Airy equation in my text is $r_1= \frac{h_1 \cdot p_u}{p_s - p_u}$. This doesn't seem to apply, or if it does it isn't obvious. Is ...
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How to graph gravity as a function of depth, given radius and density?

I need to do this for a planet that has uniform density, and a planet that has two layers. For the first part, I was given that the density was 550 kg/m³, so I made one column in an Excel spreadsheet ...
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377 views

What factors explain mountain glacier retreat variability?

It is well known that the majority of the world's mountain glaciers are retreating, but looking at a few LANDSAT images from the 1980s and today I am able to see glaciers that have retreated ...
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1answer
129 views

how much entropy is there in the shape of a rock?

If I dig up a given rock, make a 3d model of it, and compare that model with those of a large number of other rocks from the same area, what fraction of other rocks would have the same 3d model? Let'...
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893 views

What is the metamorphic field gradient useful for?

As I understand it, the metamorphic field gradient is the PT line traced out by the maximum temperature points of a series of PTt paths of rocks from the same metamorphic event. What exactly is this ...
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Which geological processes will destroy plastic?

The geological record at the end of the Anthropocene will undoubtedly contain large volumes of plastic. However, some geological processes will completely destroy plastic (e.g. magmatic or chemical ...
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Where do riverbed stones come from? [closed]

Have they always been here since the river was formed? Are some newer than others?
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628 views

Megathrust earthquakes on subduction zones

I am a beginner in geology and earthquake studies, and learning about subduction zones recently. Question is: do large earthquakes (sometimes referred to as megathrust quakes) occur on any point in ...
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1answer
209 views

How much of Earth is carbon-based? [closed]

Description Carbon ($C$), makes up for the majority of our planet and everything that lives on it. Coal, gems (any gem), plants, and most sedimentary rocks also contain great deals of carbon. Fun ...
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1answer
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What separates the Karakoram Range, the Hindu Kush, and the Himalayan Range?

In Google Maps, I don't see any boundary between the Karakoram (a.k.a. Karakorum) Range, the Hindu Kush, and the Himalayan Range. What separates these ranges?
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2answers
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What is this island or reef 600 km east of Marianas Islands?

This map shows an island a bit east of the Marianas. I took a screenshot of the relavent part. I hunted around for it in Google Earth with no luck, but I did find a promising candidate here: I could ...
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What controls the tendency of trace elements in different particle size fractions?

Trace element atmospheric particles are introduced from different sources, with both anthropogenic and natural origins. By analyzing the concentration levels of 18 elements in samples of $PM_{2.5}$ ...
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5answers
847 views

Why does mineral oil occur below natural gas?

Why does mineral oil occur below natural gas? It was asked in our science book in the Geology section and I didn't get a clear explanation from the teacher.
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Geological maps of British Columbia

I’ve been doing research into mineral deposits in B.C. I’ve been overlaying old claims maps onto Google Earth maps. Are there any good public maps for metallic minerals for British Columbia online?
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663 views

Acoustic impedance in geophysical context

What is the intuition behind acoustic impedance? Yes, I know that it is the opposition to a seismic wave travelling in the medium. But why it is defined as density × velocity? The velocity of a ...
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163 views

What controls the acidity of the ocean?

I have learned that: coral reefs are made up mostly of calcium carbonate coral reefs are mainly distributed in the tropical zone The calcium carbonate will be decomposed in the reaction as ...
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Mass balance for calculating mantle composition

I've seen some problem sets given without answers / solutions regarding how to calculate the composition of the mantle given solar composition (and assuming the same would apply to the Earth). For ...
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Are pumps used in geothermal systems?

The water held underground in a geothermal system is under high temperature and pressure. Are pumps used to raise the very hot underground water to the surface or does the water rise under its own ...
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59 views

Which geothermal power plant type is most effecient? [closed]

There are three geothermal systems that are commonly used: dry steam, flash steam, and binary cycle[1]. What are the efficiencies of the plants from best to least efficient? I did a moderate amount ...
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159 views

Can we call the Precambrian eons (i.e. Archaic and Proterozoic) eras?

A diagram in a book I have places Archaic and Proterozoic under "eras". Is such naming correct? ICS says they are eons, so do most sources I could find, but a 1979 volume of "Treatise on ...
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What type of minerals exist in this rock? [closed]

![enter image description here]Arizona desert wash A very heavy rocking have a few and when busted open beautiful veins of dark silver sometimes yellow gold.light pink and teal looking(https://i.stack....
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1answer
472 views

Oldest to Newest Bedrock in the USA “road trip”

I am supposed to design a road trip (using major highways) across North America. I have to design a route that starts with the oldest rock of Archean age and finishes with the youngest rock of ...
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2answers
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Analyzing composition of a mineral using SEM

If I have a mineral in which I did a SEM analysis on and got the data (elements and their wt% with Std. Dev., MDL, atomic % oxide % and k ratio) how would I go about quantifying the sample's ...
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What stone is this?

I don’t know much about gems so I tried to upload pictures in different lighting. The corundum pic Pictured with it was scratched by this stone. I can’t tell if the corundum scratches this stone. ...
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Radon is a naturally occurring radioactive gas. How does this work?

Radioactive rocks can release a gas called radon when they decay, which can build up in the basements of buildings with serious effects on people's health. Does anybody have information on how radon ...
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1answer
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What are these features in the Tombouctou Region?

I’ve recently been very interested in globe-trotting via Google Earth. At first I was using it to plan out hikes to possible mineral deposits locally, or potential fossils/ archeology sites. However I ...
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What is the global distribution of oil filled geodes?

In a general 40 mile radius of Keokuk, Iowa many sedimentary geodes can be found. They are abundant in the Warsaw Formation with the type section at Geode Glenn in Warsaw, Illinois. In one specific ...
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3answers
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Why does Australia have no chrome?

I've been trying to collect resource data about Australia for a few years. Some good reference sites are AustraliaMinerals.gov.au and AustralianMinesAtlas.gov.au Australia seems to be pretty rich in ...
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What is the consensus among geologists about climate change being caused by humans?

I'm terribly frustrated with the way that climate change has been debated in Europe. I live in the Netherlands and members of one of the biggest parties here, the Party for Freedom (PVV), frequently ...
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Why RBF is gridless and kriging is not?

I read about it somewhere in a paper. Why is kriging not gridless if I can krig points in space? Whats is the big difference from RBF?
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I was wondering if anyone could help me identify this rock [closed]

I found this rock along with a few other very similar ones. I found it on an island in Croatia.I was wondering if anyone could tell me the name of the rock.
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1answer
125 views

Is there a high-temperature, non-magnetic glue that doesn't dissolve in water?

I have very small mineral samples, and I'm looking for a glue that can hold them through a sample preparation process that I'm doing: heating, polishing, and measuring magnetic moment. For that I want ...
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1answer
1k views

Cause of Wallace line

First off, I am a biologist, not an earth scientist. Very recently I heard about a very interesting biological phenomenon that has its origins rooted in geology : The Wallace Line. From a ...
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4answers
554 views

What is this Lake Michigan rock? [closed]

Rock found along northern Lake Michigan, (Charlevoix, MI). Made up of very thin crystalline layers. There are small, round bubble like bumps that protrude from the surface. Doesn't show well in the ...
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3answers
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Geology: facies v. formations

Can someone please explain the difference between sedimentary facies and formations?
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For slab rollback, what allows the subducting plate to begin descending at a steeper incline?

I recently learned about slab rollback, specifically of the Juan de Fuca plate subducting underneath the North American plate. From what I understand, the subducting plate over time begins descending ...
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Is this a fossil we found in a store? [closed]

We found this rock at a mineral and jewelry store. The gal wrote down what it was and we cannot find what we think she wrote on the internet anywhere. She wrote Mcstrodlite.
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1answer
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What is this canoe-shaped rock with obsidian? flakes? [closed]

I found this rock near my home in the high desert of south central Utah (near Capitol Reef National Park). The sides are symmetrical and smooth -- shaped somewhat like a canoe. It is 6 1/2" long; 1 1/...
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Source of Dresser Formation 3.5 Ga dating

I've seen many papers and sites that give the dating of Australia's Dresser Formation as 3.5 Ga (variously 3.48 or 3.49 Ga), but I can't seem to find the source of this. Where does the dating come ...
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First stone like this [closed]

I found this stone on the bank of the Fraser River in southern BC and wonder what type of rock it is? I've never seen one like it before. Can you help me? Thank you 😀
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1answer
666 views

What does strata mean here?

What does strata mean here ? These consolidated layered strata are known as stratified rocks. The strata vary in thickness and may be tilted or horizontal. The sediments consist of loose ...
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What allowed the Himalaya to become so high?

Of course the mountains were caused by moving tectonic plates. But in case of the Himalaya mountains was the speed of the plates just higher so more energy got 'into' the mountains. Or was the ...

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