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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Has there ever been a case where we have found what appears to be a prehistoric fossil but have no way of dating it?

I find that when ever I learn of a new fossil, the age of said fossil is always mentioned. This perplexes me given how intuitively rare it seems to have radioactive material to date a formation. I ...
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Did geologists determine the age of rocks and fossils before the advent of modern scientific dating methods?

Did geologists determine the age of rocks and fossils before the advent of modern scientific dating methods such as radiometric, electron spin resonance and thermoluminescence? If they did, does ...
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What is the Pressure at the center of the Earth?

In the question below, it was determined that gravity reduces to zero at the center of the Earth. That is logical. Previous question: Does gravity increase the closer to the core you get? However if ...
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Do carbon dioxide hydrates exist in nature?

Do CO2 hydrates exist in nature? If so, how much carbon could they contain?
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Fossil ID: possible fauna fossil, from Perlis, Malaysia

I found this fossil while doing my fieldwork in limestone area. Description below may help to identify it. Location: NW Perlis, Malaysia (Setul Formation). Hilly Area. My Observation: Have a curly ...
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Rapidly rising land after rain seen in India? What can cause this?

I came across a video where a piece of land was seen rising very rapidly after rain. The land got elevated within a few minutes by atleast a meter. Can anyone suggest possible mechanisms? I am sharing ...
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1answer
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At what theoretical depth of sand would pressure turn the sand into rock?

Thinking about the movie Dune (this is not a sci fi question) got me to wondering. In the theoretical situation where you had a desert of sand with an unlimited depth here on Earth. At what depth ...
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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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Why are the mountains predominately grey or dark brown?

Observing many photos of mountains one can assume that most of the mountains are grey or brown. See also the mountain article at Wikipedia. There are however several ways a mountain can form, which ...
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Can we separate a sandy, clayey & salt layer on basis of their rheological properties?

Since, given enough compaction, salt is able to behave like a fluid & buoyant too if it's overlain by a higher density rock (it could be fine grained clay or a sandy sequence). But in another case,...
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Is it incredibly unlikely that industrial societies emerge elsewhere in the galaxy due to lack of petroleum or similar substance?

Not sure where to post this question, but it struck me the other day that the major driving force behind our modern industrial society is owed nearly entirely to the harnessing of petroleum power in ...
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What significant factors influencing geological change are still occurring?

I am teaching a secondary school course on my state's local history. The textbook begins with the history of the first humans, yet I think it is unfair not to start back much earlier, introducing the ...
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How can we know the past height of mountains?

In Feynman Lectures on Physics Volume I, Feynman talks about the relation between Physics and Geology. He says “Mountains are no lower today, on the average, than they were in the past”. Through what ...
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Is there sand in Antarctica?

There's a song "Blizzard's Never Seen the Desert's Sand". Given Antarctica is a desert, someone questioned the title's validity. BUT is there sand in Antarctica? I'd imagine yes as it's a pretty ...
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How could this pyramidal Mountain have been formed?

How could this pyramidal peak have been formed in Antarctica? Little is known about it as far as I know but what is known is that its miles away from any existing plate boundary and its shape is also ...
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How can the 'abiogenic oil' hypothesis be disproven?

We do know that complex hydrocarbons (e.g., tholins) exist in the outer Solar System. Some geologists maintain that at least some oil on Earth is of non-biological origin. The mainstream, though, ...
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Are we observing sedimentary rock formation today?

For instance, are we able to see the microscopic accumulation of shale or limestone? Can anyone reference me to sandstone formation observation, that would have to occur more rapidly. I’ve heard it ...
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How much would the ground be displaced in a magnitude 11 earthquake?

In a magnitude 5 earthquake, the ground shakes violently and it's often impossible to stay upright. This is caused by about 50-120 cm of displacement of the ground. But how much would the ground move ...
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Is it true that “[sand] grains in the Coconino Sandstone come from the Appalachian Mountains”?

The Creation Museum is a terrifying place for scientists of all stripes. One of their exhibits is the "Flood Geology" exhibit, which purports to explain how a flood of (literally) Biblical proportions ...
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How can I learn to spot fossils and fossil-bearing rocks on the Jurassic coast?

Due to a pleasant change in my circumstances, I have been to Lyme Regis several times recently, and it seems as though I'm going to be a regular visitor over the next few years. As a former biologist ...
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How is geological time divided into units?

Earth's history is divided into eons, which are divided into eras, which are divided into periods etc. Consecutive time units differ in their geology and/or fossil species. But what events are the ...
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Why do some earthquakes and volcanoes occur within plates?

I know that volcanoes and earthquakes occur on plate margins. But, do some of them also occur within plates?
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How to distinguish an explosion crater from an impact crater?

(How) Is it possible to tell the difference between a man made explosive crater and an impact crater?
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How do hematite and magnetite form?

I want to understand the conditions under which hematite $\ce{Fe_2O_3}$ and magnetite $\ce{Fe_3O_4}$ form in nature. The linked Wikipedia articles explain various conditions under which they form, but ...
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What methods do geologists employ to detemine the age of a petroleum deposit?

Petroleum is not considered a rock, but it is formed by a process, so it has an age. What methods do geologists employ to determine the age of a petroleum deposit?
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Why are South African mountains short and flat?

I drove through South Africa from Cape Town to Mozambique and noticed that almost all heights and mountains were no higher than approx 200-400 meters and had a flat top, just like the iconic Table ...
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How strong/hard are speleothems?

I want to know how hard or strong typical speleothems are. For example, could an average man break off a small stalactite or soda straw? If they're very hard, how do they compare to bone?
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Artifical Ore Genesis?

From my understanding, the formation of ores can be reduced to a simple three-step process of the removal of minerals from a source via some mechanism, the transportation of these minerals, and ...
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Can a lightning strike ionise the material it strikes?

I know lightning strikes ionise the air, but I'm looking into geology, specifically amethyst, and found that it gets its colour partially from trivalent iron, iron(III), Fe 3+, whatever you want to ...
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How fast does sand degrade into silt, and silt into clay?

I am talking to some students about how soil changes, and I've heard from soil samplers that the texture of the soil, i.e. whether it is sand, silt or clay, doesn't change in a human lifetime. It ...
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regarding four-way closure in structural geology

I am a little bit confused on the two concepts in structural geology, i.e., what is the relationship of anticline and four-way closure. My understanding is that anticline belongs to four-way closure. ...
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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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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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What is this weird looking structure in Ethiopian desert?

I was surfing through Google Maps around Ethiopian desert region (close to the town of Werder/Wardheer) and I found this weird looking structure. It seems like a dried up lake bed, but I can't guess ...
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Database of geological group or formation exposures?

Is there any sort of database that provides the locations of exposures of certain geologic groups or formations? I ask because I have read that halite occurs in the Michigan Basin, and specifically ...
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What is this geological formation in the Santa Cruz mountains that looks like a cave interior?

Stevens Canyon Road in the Santa Cruz Mountains (near Cupertino, California) passes right next to a large rock formation that, to my untrained eye, reminds me of the inside of a limestone cave. Here's ...
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Why would a suite of related rocks have one anomalous sample?

I have a suite of rocks that have nearly identical major element chemistry, but a single sample has quite different trace element concentrations. All the rocks are trachydacites. I know the analysis ...
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How can scientists be confident of isotope ratios in past eras and varied locations, used for radiometric dating?

Radiometric dating relies on past isotope ratio predictions being very reliable. However, this is not necessarily so. For example, in Uranium forensics, 235U and 238U ratios are about the same for ...
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How long does it take for a stone to alter?

We see stones and they appear to be the same throughout our life time. Mountains also appear to not significantly change. So do mountains and stones decompose? What is the life span of a stone? After ...
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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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Can a braided fluvial create thick relatively continuous siltstone beds?

I am attempting to interpret an outcrop I went to. I suggested it was created by a braided fluvial. The one thing I cannot explain are prominent alternating siltstone beds with the sandstone beds. ...
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Will California become a subduction zone in the distant future

California is one of the few places in the world that lie on a transform fault. My question is why considering the fact that North American Plate is moving westward shouldn't California be a ...
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Can I regard the grayscale of a RGB color image as a panchromatic image?

Here I have a remote sensing dataset with many bands (e.g., blue, green, red, ...), and I use the blue, green and red bands to get a true color image. I want to know if I can get a panchromatic band ...
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Why are cobalt deposits so unevenly distributed?

The Democratic Republic of the Congo's Katanga Province contains almost 40% of the world's reserves of cobalt [1]. Why are deposits concentrated so strongly in such a small portion of the earth? I ...
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Is Mount Everest currently becoming taller or shorter every year?

Is Mount Everest becoming taller or shorter every year? By how much? I would like an explanation in terms of tectonic plate movement if possible. Source: IamKatieHoffman.com
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What is a good definition of the word “rock” for teaching?

Note that it needs to include coal and chert, therefore the common answer "a rock is made of minerals" is incomplete.
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Ranking volcanic rocks influence to geothermal suitability?

I am not a geologist/geology student but I want to quickly know the influence of volcanic rock type to geothermal suitability. I have read read some journals and online articles but it seems there are ...
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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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How do the Andes get so high?

I'm interested in the limiting factors on the height of mountains. There is a very good explanation at https://www.quora.com/How-tall-can-a-mountain-become-on-Earth-Neil-deGrasse-Tyson-says-Mount-...
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How is abundance of elements in the Earth's crust estimated?

In an quiz app I surprisingly learned that aluminium has a larger abundance then iron. When researching this on Wikipedia, I found this article, which also had the comment: Note that numbers are ...

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