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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What local formation am I drilling?

I'm having a water well drilled on my property. The drilling crew has been working since Wednesday. They are using an airlift rig with a 6in bore. They are at 300ft and only have 4gpm. I would really ...
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What would a rock thin section look like without any polarizers?

I'm interested in knowing what features can still be discerned. I've been struggling find any image of a thin section of a rock under a regular light microscope, or a petrographic microscope with the ...
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What was the Earth's continent's positions 10000 years ago, or 11700 years ago, AKA when the late Pleistocene epoch was coming to an end?

In many articles online, geologists and geographers have described and depicted the theorized locations of all our continental plates with great detail and illustration, providing pictures, time-lapse ...
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Are the precious metals (silver, gold, platinum) present everywhere throughout the Earth's crust at least in the trace quantities?

Do some rocks, soils, sands or waters exist that contain fewer than one atom of gold per cubic meter or tonne of their mass?
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Geo-Spherical shape of Earth

I know that the best possible approximation of the shape of earth is an oblate sphere. But people also call it as geo-spherical shape of the Earth. What is the meaning of geospherical shape? Does this ...
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How do you choose appropriate parameters for a lowpass filter when filtering a Bouguer anomaly?

I am trying to filter my Bouguer anomaly data to remove the short wavelength features. I have created a lowpass filter to achieve this, but I am wondering how I can more objectively choose my cutoff ...
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Earth's interior heat ratio between pressure and atomic decay

What is our current understanding between the ratio of Earth's interior heat between the downward pressure and atomic decay?
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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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Storing borehole interval data (logs) in netcdf

I have a number of datasets that describe geological properties as intervals down a borehole (e.g. unit codes, sample results) In a database, or a flat ASCII file, I would describe these with a ...
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Why does Morocco have so much phosphate?

I read that Morocco/Western Sahara has 75% of the world's known phosphate reserves, but I couldn't find an explanation of what mineral is responsible for it and how it all ended up there.
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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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Have fossils ever been found in the asphalt lakes of Trinidad and Venezuela?

La Brea tar pits in California are the result of ancient oil seepages and famous for the fossils of extinct animals which were trapped in the tar. The asphalt lakes in Trinidad and Venezuela are also ...
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Where and how big was Sicily between 5 and 1 Ma ago?

Sicily is a geologically complex island which seems to have been extensively studied geologically and from a tectonically point of view. There are an overwhelming number of papers dealing with the ...
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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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What are the favourable conditions for the formation of porphyry copper deposits?

Favourable condition for the formation of porphyry copper deposits is : 1. Extremely low oxygen fugacity in initial magma 2. High water content in initial magma 3. Crystallization of magama at deep ...
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Sources or strategies for stone identification

I have a bunch of semi-precious stones here, but I am not very learned in geology etc and I would like to have some way to know what kind of stones they are. As far as I understand question about ...
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Luis Alvarez's K-T Impactor Calculation

I am trying to perform the calculation that Luis Alvarez used to establish the size of the K-T impactor. I used the following information: Assume that the clay layer with iridium was uniformly ...
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What ore minerals are likely to be found in a thin section like this? What can we deduce from the structure?

The following image is of polished sample of mineral-rich rock. There are two major portions we can see that is ore minerals and rest the grayish material is gangue. The photo was taken with an ore ...
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How are stratigraphic limits defined before the Phanerozoic?

International Commission on Stratigraphy defines the limits of geological ages and they create this chart: Click on image for full view. Acording to Wikipedia: The standard stratigraphic ...
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Faster shale velocities in deviated wells

I am currently working with sonic measurements in the wells and there is an observation, that velocities are faster in shales over the deviated parts of the well. So, when the relative dip between the ...
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What are the key elements defining the separation between Jurassic and Cretaceous?

We have one mass extinction that seperates Trias from Jurassic, roughly huge volcanims over a long period of time, and Pangea starting to divide. Another mass extinction that marks the end of ...
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4 votes
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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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Do we know what the rigid mantle looks like?

The rigid mantle, which is hard and lies above the asthenosphere, is separated from the "crust" that we can see and touch by the Mohorovičić discontinuity. Wikipedia provides an image of what may once ...
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Does gravity increase the closer to the core you get?

Or does the mantle and crust above you counteract the increase at one point and it actually decreases?
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Are there any known global effects of the Mediterranean sea evaporation and refilling?

This is a broad subject I realize, but I'm looking for specific geologically observed answers of global effects elsewhere, between about 5.96 and 5.33 million years ago when the Mediterranean sea was ...
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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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How to genetically classify a mineral resulted from weathering?

I am writing a mineral guide for smartphones which classifies minerals according to their formation environment. From sugestions on this related question, I changed the classification to: ...
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Waves in very thin layer

Elastic waves in the earth are described by the elastodynamic equations \begin{align} \rho \frac{\partial^2 u}{\partial t^2} &= (2 \mu + \lambda) \frac{\partial^2 u}{\partial x^2} + \mu \left( ...
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What is the difference between mobile & molten rock?

In the book Fundamentals of Geomorphology (Routledge Fundamentals of Physical Geography) by Richard John Huggett there is a sentence " Intruded rocks, which must be mobile but not necessarily molten,...
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How to make Martian soil [duplicate]

My son wants to replicate some experiments and try to grow plants in Martian soil for his A-level science project. I know NASA have managed to produce soil that mimics Martian soil, however I also ...
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14 votes
3 answers
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How to make Martian soil

My son wants to replicate some experiments and try to grow plants in Martian soil for his A-level science project. I know NASA have managed to produce soil that mimics Martian soil, however I also ...
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6 votes
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Considering the thin piece of material on the surface of Mars in the image below, is there anything like it on Earth?

The above is a magnified part of the original image below captured by the Curiosity rover on Mars on sol 1729 (June 17, 2017). From the added information with that raw image it can be estimated that ...
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Puddingstone info sign for Trail Store

I run a Trail Store (sell hiking maps, swag, etc) in Mahwah, NJ, USA. I'm trying to feature a plant and rock every season. The first rock chosen is puddingstone. I created the short sign below, ...
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How likely is Earth to naturally reverse climate change in the next 2 decades?

A new decade question: given that the “mini ice ages” were triggered by volcanic activity, how likely is it that we will experience similar levels of volcanic activity over the next 20 years? In ...
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1 vote
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Centripetal Force Perfect Ball and Water

I made a question in WolrdBuilding as I was directed to. There a user said that with a perfect ball all water would pool to the equator because of centripetal force. What I do not understand is how ...
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Where can I find broadband seismic reflection data?

or what type of companies should I contact to ask for the data? This data would be produced from Seismic Vibroseis survey trucks which are mostly used to locate oil and gas. I doubt most oil and gas ...
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About climate sensitivity of carbon dioxide: today compared with PETM

Due to IPCC the climate sensitivity of CO₂ very likely is 3.0 ± 1.5 ℃ for each doubling of the concentration of atmospheric CO₂. Counting on earlier global warming using the Arrhenius formula [ΔT=λ·...
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Are there any geology only related educational institutions?

I'm not looking for college recommendations or which is the best, so I'm not asking for opinions on which institutions are the best. What I would like to know is if there are specific places that ...
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What is the history of atmospheric O₂ concentration?

(This is about O₂, not CO₂) How did the concentration of oxygen change? Over geologic time frames since plants began to produce it, and during the time since the carbon dioxide increase caused by ...
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5 votes
5 answers
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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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Inquiry, Is this Crystal? [closed]

I'm Erfan from Yemen, I found this stone in my village's mountain, it looks not normal stone, it's shinning like a crystal and headlight can penetrate it. There are hundreds of it in the mountain. ...
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3 votes
3 answers
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Formation of Iceland

Iceland sits atop a divergent ocean-ocean boundary. But there are not many islands which are formed along a divergent boundary. Why is it so? Why do not mid ocean ridges often rise above the sea ...
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1 answer
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Origin of Andaman and Nicobar islands

Are Andaman and Nicobar islands in Indian ocean a continuation of Alpide-Himalayan orogeny or are they volcanic in origin?
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How can one find the true dip angle and quadrant when an apparent dip and strike is provided?

I am trying to solve the following question but cannot figure out how: A layer of limestone has a strike of East to West on a hilltop, and an apparent dip of 40 degrees on the vertical hillside ...
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3 votes
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Strength of Magnetic Field at Mid Point of a Reversal

As the duration of a magnetic reversal can be up to 12,000 years, could there come a time mid-way in the transition when Earth's magnetic field is as negligible as that of Mars or Venus? Magnetic ...
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4 votes
1 answer
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What's the story of the shear face in the new Mac OS Catalina wallpaper?

The new Mac OS boasts a beautiful default desktop background with the western tip of Santa Catalina Island. The rock formation in the foreground looks like it was sliced on the diagonal with a power ...
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Paleogeographic Map

How do you construct a paleogeographic map with given sedimentary structures as guidelines?
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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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3 votes
1 answer
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How did these dark lenticular features form? (Near Hoganekkal Falls India.)

These photos were taken near Hoganekkal falls in south India. The darker lenses appear to be the same rock type but have varying thickness and do not form a continuous layer. How did this structure ...
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5 votes
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Is this classification of mineral formation environments correct?

I am writing an app for students that consist in 180 sheets of the most common minerals on Earth's Crust. One of the fields of the sheets is environment of formation. It is important to me to ...
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