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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Extinctions and geomagnetic inversions

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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Formation of Hematite on Mars via Perchlorates as an Oxidizer

Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity. A comment to the answer to the question: How do hematite and magnetite form? states that ...
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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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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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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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Rocks sparking under water

I have searched for an answer to this question for years, to verify if it was true. A man that lived on a river in the rugged part of the northern Washington Cascades told me an interesting story. He ...
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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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What caused the bend in the Emperor/Hawaii chain of islands, 45 million years ago?

What caused the bend in the Emperor/Hawaii chain of islands, 45 million years ago? Has there been any updates to this mystery I am unaware of? Are there any new theories that could potentially ...
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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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How long could a steel artifact last?

Would man-made steel artifacts be able to be preserved like fossils for millions of years, or would corrosion make them dissipate? What about metals such as aluminum that don't corrode as easily?
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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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Why are there more intense earthquakes in Iran than in Iraq?

Why are there more intense earthquakes in Iran than in Iraq, if they are so close together? I often hear news items of earthquakes in Iran that are higher on the Richter Scale than those that happen ...
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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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Has a scientific consensus been reached concerning the formation of the Grand Canyon?

new student of Oceanography here! I'm studying Earth Science right now, and I found conflicting reporting re: the formation of the Grand Canyon; whether it was formed singularly by the Colorado ...
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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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Quartz mineral category

Different learning resources categorise quartz differently. Strictly speaking, is quartz a silicate mineral or an oxide mineral?
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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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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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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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How ocean pockmarks are formed and how quickly? [closed]

I couldn't find much information about it on google and I don't know much about how pockmarks work.
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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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How high can a mountain possibly get?

Mount Everest is 8,848 metres (29,028 feet) above sea level and is the result of a continental plate smashing into another continental plate. Can a tectonic process build a mountain that's even higher?...
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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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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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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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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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Chicxulub Asteroid Remains?

Do scientists know if the Chicxulub asteroid disintegrated completely upon impact or if any (large or small) chunks of the asteroid remained intact? If it is possible that a significant fragment of ...
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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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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 many extreme shifts in climate has Earth gone through in its existence?

As the Earth formed, it went through cycles of essentially hotter and colder periods. Extremely volcanic times and ice ages, in feedback loops contributing to one another. CO2 swinging from high to ...
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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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Looking for a complete table of minerals for a database

I am building an open source spatial geochemical/geological observational database for mineral exploration. I need to fill the mineral lookup table. Where can I find a complete list of all minerals ...
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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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Introduction to Geology Books

I am a high school student who is thinking about going to university for Geological Sciences. I've had an interest in rocks and such since I was little, but I want to get an idea of what studying ...
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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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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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Why isn't Iberia a tectonic plate?

I usually read that Iberia is a subplate, while India is a plate. But it was a plate at the beginning of the Alpine Orogeny: Source: wikimedia.org Description: Tectonic map of southern ...
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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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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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How to read stratigraphy data?

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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Is it true that earthquakes are not felt in a cave?

I took a tour of a cave in northern California last weekend. The tour guide asked us, "If an earthquake occurred, what would we feel in here?" My answer was, "fear," but she said we would feel ...

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