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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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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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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Are coral cays and coral atolls just volcanic islands?
Are coral cays and coral atolls just a different type of volcanic island? When I hear: "volcanic island" I think at places like Moorea or Hawaii, but ultimately, coral cays and coral atolls lay their ...
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Why do fjords have sills?
I have read about some of the geologic processes that are related to the formation of fjords. Is the presence of sills in fjords related to the deposition of glacial moraine?
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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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Measuring bed dip angle from contour lines, which lines to pick?
Measuring dip angle of a bed, I choose any 2 contour lines that cross the bed, and then project lines off and measure the angle (I'm assuming this is standard technique that doesn't require ...
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Magma resultant from group 1 and group 2 elements?
I was recently speaking with a geology professor over lunch at a university who has a theory that I've never heard before. His postulation was quite compelling and I was hoping to do a little digging ...
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How are spherulitic structures formed in basalt rock?
After having studied the thin sections of basalt under the microscope, I have come across many spherulitic structures occurring in clusters.
How can this happen?
Is it due to devitrification or is ...
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What is the long term impact of large scale removal of material from subterraneal caches on the structural integrity of the soil?
For example, sinkholes can be human induced:
New sinkholes have been correlated to land-use practices, especially
from groundwater pumping and from construction and development
practices. ...
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How did the Cliffs of Dover form flint in regular stripes?
The White Cliffs of Dover are mostly chalk but there are regularly spaced horizontal lines of flint.
I understand how the chalk and flint layers are formed independently (from Wikipedia) but I haven'...
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Seeming correlation between time of day and earthquakes
I live in a generally geographically active area (Southern California, near the San Andreas fault, if that matters), that has had two relatively minor earthquakes that I have felt in the last week (in ...
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Cause of Wallace line
First off, I am a biologist, not an earth scientist.
Very recently I heard about a very interesting biological phenomenon that has its origins rooted in geology : The Wallace Line.
From a ...
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Math needed for Hydrology, specifically surface water hydrology
I wanted to know what math is needed for hydrology, in particular surface water hydrology.
In my research online, of Master's programs (either in Hydrology or Environmental Science with a ...
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What determines when the end of a volcanic eruption will happen?
The Cumbre Vieja volcano of La Palma Island, Spain, started to erupt 3 months ago.
This week, the volcano stopped emitting lava and there remains only degassing processes. According to this news story,...
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Will a Mohs hardness scratch pen need to be replaced or resharpened?
I am considering buying a set of Mohs hardness scratch pens (aka hardness picks). As a hobbyist the price is quite high, starting at 300 USD and upwards for a complete set. I can accept this price if ...
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What controls the acidity of the ocean?
I have learned that:
coral reefs are made up mostly of calcium carbonate
coral reefs are mainly distributed in the tropical zone
The calcium carbonate will be decomposed in the reaction as ...
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What is this strange formation near Râmnicu Vâlcea?
So I was browsing Google Earth the other day and I found this strange formation near Râmnicu Vâlcea, at about 45°07'N 24°16'E
It's an almost circular region, about 40 km in diameter which to my eyes ...
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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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Why do the earth sciences use mega-annum instead of mega-year?
I've noticed that geology and related fields use mega-annum (Ma) instead of mega-year (Myr) as the unit for 1 million years. Why is that? Is an "annum" different from a "year" in geology?
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The different types of plagioclase
The fractions of albite $\ce{NaAlSi_3O_8}$ and anorthite $\ce{CaAl_2Si_2O_8}$, which I call $\ce{Ab}$ and $\ce{An}$ in the following list, present in a plagioclase are often used to define it in the ...
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Why is Michigan Geology Circular?
Looking at maps of the geological layers in Michigan it looks like an onion starting in the center of the state. Why?
Thinking of the recent glacial history of the state that would seem to have ...
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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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Are old geophysics textbooks useful?
I have had much success with old textbooks in mathematics. Generally, for any branch of mathematics that I (as a non-mathematician) would like to learn or re-learn, I can buy a classic textbook from ...
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Difference between "Geology" and "Physical(Natural) Geography"?
I know "Geology" is a branch of "Natural sciences" and is for studying natural and physical phenomena related to earth. But "Physical Geography/Natural Geography" seems to study exactly the same thing....
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Round structure in southern United States
Assuming here might be someone who knows something about this, I wanted to ask what is behind this round structure I have spotted today on Google Earth:
There seems to be a large (~200 km), nearly ...
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How does one create petroleum/crude oil for future generations?
I am a geological novice so maybe this is a wrong question. But the idea is to create a thought experiment. How does one "create" petroleum or crude oil for future generations? Is it enough to bury a ...
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Where can fluorite be found on Long Island, New York?
I'm interested in fluorite (Since Fluorine is my favorite element, and I wanted a sample of it, even if bonded, but I don't want to buy it; that would be no fun), and I'm curious if it can be found on ...
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Newton's estimate of the age of the Earth
I was reading many articles about estimates of the age of the Earth throughout the ages. I was dumbfounded when I read that Newton, arguably one of the greatest scientists ever to have ‘calculated’ ...
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Himalayas are currently rising. What will be the highest point they can reach?
Himalayas are currently rising about 5 mm/year. What will be the highest point they can reach?
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What caused this waterfall to have rounded formations?
This is at Bua Tong Waterfalls in Chiang Mai, Thailand.
Tried to find scientific information about this waterfall, but google turns up only travellers' vague guesses, suggesting calcium carbonate ...
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In an Earth-like planet with no history of carbon-based life forms, would there be limestone?
The extent of my understanding of limestone is about what Wikipedia says at the very top of the page:
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such ...
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How is/was continental drift monitored?
I am curious about current technology but I am particularly interested in what techniques were employed prior to the advent of satellite technology.
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Could the Grand Canyon be flooded by the ocean if it got deep enough?
The Colorado River has been carving the Grand Canyon for a few million years now, such that the canyon floor is around 6000 feet lower in elevation than the surrounding area, at about 2400 feet above ...
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In the oil field, when a vertical cylinder coring sample is taken, how is the core severed at the bottom and removed from the formation?
I would like to know how the core is cut off at the bottom of the drill. I also would like to know how the core is brought up to the surface without slipping out and falling back down.
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A circle shape in Madagascar
I was seeing Madagascar on Google Maps and accidentally i saw a circle shape near Bebao. Coordinates are 17.4317443°E and 44.644248°S.
Please, to satisfy my curiosity, can you tell me why is this ...
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Is it possible to create clouds by pumping water into volcanoes?
Suddenly, there is this idea in my mind that if an important effect of global warming is rainfall reduction and drought, is it possible to use volcanoes as water vaporizers (regardless of costs)?
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What causes such a narrow slit in a cliff? (see photo)
I have this photo as a background image and I often wonder how such a narrow, well-defined slit could be formed. Is it natural or man-made? If natural, what processes could have formed it? The rest of ...
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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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How can smartphones help geologists in the field?
Smartphones have incorporated many sensors and some of them can be helpful for a geologist in the field:
They have GPS, so it is possible to register your route in a Google Maps map. I find this may ...
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How old are Chile's fjords?
Do we have any knowledge about the age of Chile's fjords, more specifically, those found near the Northern Patagonian Ice Field?
Is it reasonable to conclude that they were formed in Quaternary given ...
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How straight is the Kola superdeep borehole?
The legendary Kola superdeep borehole is about 12 km deep. To achieve such depth, a major difficulty is to make sure the borehole is vertical straight.
Intuitively, when the borehole is deep enough, ...
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What are the craters and mounds in this Missouri bedrock map?
When looking at this map of bedrock geology of the Illinois and Ozark basins (sourced from Geological and Geophysical Maps of the Illinois Basin-Ozark Dome Region),
I can't help but notice that ...
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Will another big earthquake hit Kathmandu?
Recently, we got the news that the western part of Nepal may be hit by a larger earthquake than that of April 25, because it did release all of its energy. During the earthquake, only the eastern part ...
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Extent of the Persian Gulf
Is there a consensus on when the Persian Gulf reached its modern day levels? So far the material I have read says the Persian Gulf attained its present levels around 4000 BCE, but I am not too sure. ...
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How long does one touch on a stalagmite/stalactite lasts?
There is a discussion about whether touching a stalagmite or a stalactite would stop it from growing or not: https://answers.yahoo.com/question/index?qid=20090629155053AAYFhCM .
The results are that ...
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Does the high pressure inside the Earth's core contribute to its high temperature?
The explanations for why the Earth's core is hot I found on the internet included:
leftover energy from the Earth's formation
radioactivity of the elements inside the core
friction between the core ...
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How do the swirls and veins in marble form in detail?
I am finding surprisingly little information about this. I imagine that the process is somewhat like foliation except because the particles that go into marble (to my knowledge) don't have any ...
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How are chenier ridges and strand plains formed at wave dominated coastlines?
In the attached image, we can see chenier ridges and strand plains. How are they formed and what is the involvement of rip and longshore currents in their formation?
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What is the rock I found on the Delaware river yesterday? [closed]
I spotted this large striped rock found on Delaware River. Note the fossil in the first picture. What kind of rock is this?
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Alpine schistosity
I often find the term Alpine schistosity (schistosité alpine in French, scistosità alpina in Italian) in texts about Alpine geology. Chronologically ordered phases of Alpine schistosity producing ...