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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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 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 to calculate mountain front sinuosity index using DEM?

In tectonic geomorphology the Mountain front sinuosity index is one of the morphometric indexes. Smf = Lmf/Ls I have a DEM, so how do I use it to find the value? According to this diagram do I have ...
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Extinctions and geomagnetic inversions [duplicate]

The article Did the Earth’s magnetic field affect our evolution? on Pledge Times cite this Science paper to assert: These authors speculate that, in the Pleistocene, large mammals could have reached ...
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Complete missing outcrop problem

Given A is upper limit of sand stone, B is the lower limit of the planes that are equal in distance and dip. Dip angle is 29 degrees. Complete the outcrop of this map. —————————————————————————- Now I ...
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What kind of rock is this? [closed]

A few years ago in Venezuela, parque nacional de Cainama, the tourist guide found and gave me this rocks, he told us that a geologist told him that those could be radioactive but no one believed him. ...
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How did this stone become encased within different rock?

My father, in his younger years, was a stone mason in Cincinnati Ohio. A couple of decades ago he was building a wall of some kind. He would fetch rock from a creek bed, haul it to the construction ...
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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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Is there any intuitive and easily understandable way to help students understand the triangular facet of outcropted stratigraphy?

I find it difficult to teach college students about using the triangular facet on remote sensing images to judge the dip direction of sedimentary formations. Is there any intuitive way that can help?
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Are these igneous Liesegang rings on a popular Oahu, Hawaii hike?

I hiked the Lanikai Pillbox trail (Oahu, HI). I noticed eroded concentric rings in the igneous rock with a hard center. I'm unable to find the geologic cause of these rings. Are they Liesegang rings? ...
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Term for the Process of the Early Earth's Crust's Changing Mineral Composition

In the book, Story of Earth-The First 4.5 Billion Years, From Stardust to Living Planet, by Robert Hazen, Chapter 3: He discusses the changing mineral composition of the early Earth's crust from ...
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How can we distinguish fold and cycle of sedimentation on a remote sensing image or in the field?

A fold is composed of stratigraphy that is symmetric and repeated. Cyclic sediments (also called rhythmic sediments) are sequences of sedimentary rocks that are characterised by repetitive patterns of ...
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How much earth has to be moved to get one tonne of copper

I am trying to make sense of the mining process of minerals or metals. I found two measures related to waste: the stripping ratio (which is usually larger than 3:1 for copper, i.e. 3 tonnes of waste ...
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Differentiate correlation of between depth and bouguer anomaly

Assume we measure bouguer anomaly (g) and depth (H) of the certain horizon through a profile at each point. Based on data we get a correlation between H and g and express it with a polynomial equation ...
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Hypothetically, in the near future, could gas hydrate pingos erupt?

Could gas hydrate pingos erupt? If so, how quickly? And how much CH4 could they release? I'm sorry if the questions sounds silly. I'm new here and I don't know much about gas hydrates and oceanography....
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Ore prospecting and the low-hanging fruit effect

I'm trying to acquire an understanding of how the difficulty of prospecting for useful ore has increased over historical timescales. Intuitively, I would expect that centuries or millennia ago, you ...
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How to add scale in DSLR plus microscope set up by default?

We have an Axioscope microscope and planning to install a Nikon D5300 camera on top of it. The software I looked up, is DigiCam Control. The downside is we cannot add scale by default. The scale has ...
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Permeability test

What are the different ways permeability of a core specimen can be determined accurately for fluids with different viscosities and their mixtures?
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Ore Deposit Identification

What type of ore deposit does this rock best represent? A rock with a porphyritic texture is cross cut by a stockwork of quartz veins. Bordering the veins is extensive alteration of the host rock. ...
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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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Feldspar content of coarse-grained igneous rocks

From the chart, I would say that plagioclase feldspar is more abundant in coarse-grained igneous rocks than alkali feldspar, as it is found in all three listed, whereas alkali feldspar is only present ...
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Quartz mineral category

Different learning resources categorise quartz differently. Strictly speaking, is quartz a silicate mineral or an oxide mineral?
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Coarse grains in a sample of Rhyolite suggest that it formed by

Coarse grains in a sample of Rhyolite suggest that it formed by …… A-rapid cooling of molten rock materials at the Earth’s surface. B-slow cooling of molten rock materials at the Earth’s surface. C-...
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Cleavage of minerals

What is the difference between 3-dimensional cleavage and cubic cleavage? I think, they are the same, but I am not sure about if I was right or not.
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puzzling statement on earth history!

A Geology proffessor recently told me that around 200,000 years ago, when homo sapiens emerged, that "...all of civilisation can now fit on the width of a single strand of human hair." I am ...
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Arabian Desert rock formation

I'm interested about this rock formation in Arabian desert. The rock looks like melting chocolate. Not sure where the exact Location, the source says it around Al-Ula, Saudi Arabia. Here the image ...
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How do geologists measure green house gass emmissions from large regions

I read here that volcanoes release about "0.6 billion metric tons of carbon dioxide per year". I wonder though, how scientists can estimate the emissions from large regions with geological ...
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Hydrocarbon resources extension. How?

Pardon my naive question. But I heard this argument quite sometimes. One can find at the Schlumberger careers page the particularly interesting FAQ: “We are often told that oil is running out. Why ...
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How do long, thin, island chains such as North Carolina's outer banks, form?

I can't think of a possible explanation, there's no volcanic activity in the area, and it gets destroyed every time a hurricane passes through. How did it get there?
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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 to read stratigraphy data? [closed]

I have a list of geological data. The data is for 3 variables: member, level and L+/- These variables correspond to a particular position on a stratigraphic column/chart. I would like help with ...
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How can the 'crystal cleavage' of apatite have a four-digit number?

On Wikipedia's page for apatite, the crystal cleavage is listed as [0001] or [0101], which I assume are Miller indices.... But how can there be four numbers/digits instead of two, like there usually ...

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