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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Sediment layer chronology

In the new Cosmos series, Neil DeGrass Tyson in explaining different ways the age of the world has been determined, shows how sedimentary layers at the Grand Canyon are a fossil record of a lot of the ...
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How can the 'abiogenic oil' hypothesis be disproven?

We do know that complex hydrocarbons (e.g., tholins) exist in the outer Solar System. Some geologists maintain that at least some oil on Earth is of non-biological origin. The mainstream, though, ...
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What color(s) would Earth be without water or life?

Many of the celestial bodies in our solar system have well-established color schemes, at least in the minds of the public. Mars is pale-red and black, Venus (beneath the clouds) is generally shown in ...
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Database of geological group or formation exposures?

Is there any sort of database that provides the locations of exposures of certain geologic groups or formations? I ask because I have read that halite occurs in the Michigan Basin, and specifically ...
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Is Zealandia really big enough to be called a continent?

I was reading this article about Zealandia and got excited that there could be an underwater continent. However, when viewing the image (below) it appears that Zealandia is much smaller than any ...
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What's the geological period of the birth of the river Ganges?

Avatarana or Descent of the Ganges (extracted from Wikipedia): "In late May or early June every year, Hindus celebrate the avatarana or descent of the Ganges from heaven to earth." There are ...
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Which geological processes will destroy plastic?

The geological record at the end of the Anthropocene will undoubtedly contain large volumes of plastic. However, some geological processes will completely destroy plastic (e.g. magmatic or chemical ...
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Rate of underground formation of carbon-14 by neutron capture

Carbon-14 constantly forms in the atmosphere due to neutron capture by nitrogen-14 and subsequent emission of a proton. Other less frequent mechanisms involving neutron capture by carbon-13 or oxygen ...
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What is this weird looking structure in Ethiopian desert?

I was surfing through Google Maps around Ethiopian desert region (close to the town of Werder/Wardheer) and I found this weird looking structure. It seems like a dried up lake bed, but I can't guess ...
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Why is the concept of “mass extinction” a relatively recent development in geology?

The concept of "mass extinctions", with its catastrophic connotations, is a relatively recent development in the geological sciences. It evolved in the early 1980s, driven by two landmark publications ...
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What is the reasoning behind the statement “Faulting will occur along the plane where the shear stress is the highest”?

In "An Introduction to Seismology, Earthquakes and Earth Structure", authors Seth Stein and Michael Wysession made the statement: "Faulting will occur along the plane where the shear stress is the ...
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What do you call boulders of non sedimentary rock that were lithified into sandstone?

I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes ...
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How do I prepare for the International Earth Science Olympiad?

Recently I have been selected for the National Camp of INTERNATIONAL EARTH SCIENCE OLYMPIAD of my country. How do I prepare for it? Resources, books, etc. I know there are 4 parts- geology, ...
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What is the geologic origin of Cryolite, and could there be more?

Cryolite is a mineral of aluminum (Na$_3$AlF$_6$). The only known natural deposit was found in Ivittuut, Greenland. It was mined from 1854 to 1987 and yielded 3.7 Mt of Cryolite ore. Basically my ...
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Earthquakes at plate boundaries

I was looking into tectonic plate boundaries and earthquakes with pictures like these One thing that is quite obvious is that some of the plate boundaries have very thin zones of earthquakes, ...
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Rock ID: a black rock/lava? around another white rock, unknown location [closed]

I tried to look for any similar rocks on the Internet but couldn't find anything and I don't know much about geology. I've been given this rock when I was a child and now I'm just curious to know ...
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Is altitude of everything decreasing due to sea level rise?

We know that sea level is rising, though some people say climate change is fake. Altitude is defined as the height of something measured from sea level. Since sea level is increasing, and the ...
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What is the current status of geophysical global cooling theory?

Plate tectonics effectively rubbished the theory of geophysical global cooling as a means of explaining many surface features on the Earth. However, this wiki says that the same process is responsible ...
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How deep are the cracks in the earths crust at fault zones?

I have seen pictures of the cracks in the Earth's crust in Iceland and the San Andreas fault. To my eyes, the crack is relatively wide at the surface than a few meters down seems to be very narrow or ...
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Is it ever possible for an continental plate to subduct under an oceanic plate?

It is well known that oceanic plates subduct under continental plates. This may be attributed to the plate's age and density, plus the water on top of it. So I was wondering if it is ever possible for ...
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Why are there no deep caves in the continental US?

According to http://www.caverbob.com/wdeep.htm and http://www.caverbob.com/usadeep.htm, the only cave over 1000m deep in the US is a lava cave in Hawaii. In the continental US the deepest is 505m. On ...
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Impact craters vs volcanic explosions on Mars

A maar is a shallow volcanic crater with steep sides that is surrounded by tephra deposits. The tephra deposits are thickest near the crater and decrease with distance from the crater. Source: http://...
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Did an impact crater influence the formation of uranium deposits in South Australia?

As a supplementary question Did an impact crater cause the formation of the gas fields in north eastern South Australia . South Australia is a well documented uranium province. Could an impact crater, ...
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How has the relative ratio of igneous, sedimentary, and metamorphic rocks changed over Earth's history? [duplicate]

Has the relative ratio of sedimentary over igneous rocks increased, simply as a result of more and more of the Earth's rock being exposed to sedimentary processes? Or has it increased only for the ...
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What is this brown and white rock? [closed]

We found this rock in our backyard. Could someone please tell me what it could be?
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How accurate is the law of superposition?

Recently I started being more interested in the rational details of the sciences (... being often challenged about them by a creationist friend) and one of the creationist 'theories' I've encountered ...
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Are there minerals which are not been found on earth but which are still possible to exist?

On Earth we find many kind of minerals, a lot of them are silicates. How much different kind of minerals would there be on Earth? But are there Fe minerals found in meteorites which do no occur on ...
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How long does it take for a stone to decompose?

We see stones and they appear to be the same throughout our life time. Mountains also appear to not significantly change. So do mountains and stones decompose? What is the life span of a stone? After ...
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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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What is this blue rock? [closed]

I am trying to identify a rock my husband found.The rock was found in Columbus Ohio about 20 feet (6 m) down. It is about the size of a basketball and extremely heavy (90 lbs) and difficult to cut ...
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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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Rock ID: shiny, very hard, black rock from Louisiana, USA [closed]

I have had this for over 20 years and I still don't know what it is. I found it on top of the ground by my dad's workshop in our yard in Louisiana. I don't know how it got there. It weighs 6 pounds 7 ...
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How can I learn to spot fossils and fossil-bearing rocks on the Jurassic coast?

Due to a pleasant change in my circumstances, I have been to Lyme Regis several times recently, and it seems as though I'm going to be a regular visitor over the next few years. As a former biologist ...
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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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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 type of rock is this paving stone and what is the origin of the red colouration? [closed]

This paving slab is part of the floor of the new atrium in Kings Cross Station in London: The paving slabs are mostly grey but some contain areas of this reddish colouration. They are all fine ...
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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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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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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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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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Rock ID: brittle black/white w/ crystals & mica-like cleavage layers, Raleigh, NC, USA [closed]

Where it was Found: I found the rock laying on the sidewalk near some landscaping at my apartment complex in Raleigh, NC. Size: The largest intact portion of the rock is about 2.2 cm in diameter. ...
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What kind of a rock is this (from Finland)? [closed]

I found this rock at my friend's summer cottage in Finland. I have never seen a rock like this in my life. It resembles a lava stone, but Finland isn't a volcanic country. I am no expert in geology ...
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What is this Cape Breton rock? [closed]

What is this rock? I found it in Cape Breton, Canada
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Can a 99.9% probability of an M≥ 5 earthquake within a 3-year period be verified?

Paper: Potential for a large earthquake near Los Angeles inferred from the 2014 La Habra earthquake (2015) Obviously there has been much discussion on the viability of earthquake prediction. This ...
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Rock ID: Large, heterogeneous, magnetic rock in Cascade Range, Washington, USA [closed]

I found this rock in a glacial till in north central Washington State, on the east side of the Cascade Range. The dark round crystals are roughly 1 inch (2.54 cm) by 2 inch (5.08 cm) in size. The ...
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What kind of rock is this gray and brown weathered cylinder-shaped rock I found near a New York lake? [closed]

I found this rock on the beach of a freshwater lake in the Finger Lakes region of New York state and am interested in knowing more about it. It is about 2" tall and 2" wide at widest point. Weighs 14....
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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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What is the global distribution of oil filled geodes?

In a general 40 mile radius of Keokuk, Iowa many sedimentary geodes can be found. They are abundant in the Warsaw Formation with the type section at Geode Glenn in Warsaw, Illinois. In one specific ...
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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 ...