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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16 views

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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57 views

How do you infer what a cross section might look like below sea level?

Here is a schematic of a cross section which should represent an anticline: https://postimg.cc/4HcmmZ26 Below sea level, I have inferred what the units might look like with the dashed lines. As I have ...
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What is the best way to split strike and dip data on the image provided into “domains” in order to interpret folding on a stereonet?

Link to the original image: https://postimg.cc/v4bRqxxR I believe this image represents two folds which are overturned and plunging. I would like to analyse these folds on a stereonet, but I am unsure ...
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Why is Earth's density gradient a step-function, rather than smooth?

Why is the density of particles in Earth's atmosphere above surface-level so much less than ground and below? Why, instead, isn't Earth simply a ball of swirling gasses / liquids, which become ...
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Are metals and other elements in every continent?

I originally thought that you can only find certain things like iron, copper, and other things in certain places in the world and deep in mines but I saw in a few YouTube videos that you can find iron ...
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Are Fluvial and River Terraces the same?

I study about fluvial terraces. However, resources related to this topic are limited. When I searched fluvial terraces in geomorphology books, I cannot find anything, but I find river terraces. My ...
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What happens when a mid-ocean ridge sub-ducts underneath continental crust?

I'm aware that oceanic crust always sub-ducts to continental crust, but surely the geologic forces pushing the ridge apart in the first place isn't just going to turn off, right? Any answers would be ...
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Question Concerning Meteorite Ejecta Travel

I was researching more into the studies done by Kjaer and his team ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235527/ ) concerning the hypothesis about the Younger Dryas impact crater named ...
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Identifying thrust faults on a geologic map

I am not able to upload the map as the file is too large, but I have a map which states there is an over thrust fault. It has two ticks on it indicating downthrow to the NE. The downthrow is pointing ...
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Is it a Lake, Cove, Tidal Creek or a Spring?

We are very confused by this water body. This is called "Carolina Lake" however other suggests that it is not a Lake but a cove. Other say it is a tidal creek for it is influenced by tide. ...
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How would one go about drawing the contour lines for this map in order to draw the cross section?

Good Day. We Received this map as practice for our Geology university module and I have no idea how to draw the strike lines where the different heights intersect the different rock types in order to ...
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Structural geology

Map 4 shows two dykes that have been offset by a vertical fault. In different coloured pencils, draw strike lines on each dyke. (a) On a blank sheet of paper, use the strike lines that you have drawn ...

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