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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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Icelandic rock I am trying to identify

This is a rock that I picked up from underneath a melted segment of Glacier in east Iceland. It is not unusually heavy or light for it's size. I can scratch the surface away with a penny. The ...
6
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1answer
279 views

Hydrocarbon potential in Ganges Brahmaputra delta

According to Curray (1991): Total sediment thickness beneath the [Ganges–Brahmaputra delta] southeast of the hingezone exceeds 16 km... Considering a normal geothermal gradient and data for oil ...
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Why did people draw so many continuous squares in the sand on the beach at Cape Juby?

At Cape Juby, Morocco, we can see with Google Maps a rectangle of 3 km long, in which there is hundreds of little squares. What method was used to draw these squares on the sand? More importantly, why ...
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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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Is there a difference between rock and stone?

I couldn't find the definitions from either source: Geology Dictionary Glossary of Geologic Terms
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182 views

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 ...
7
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1answer
281 views

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 ...
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509 views

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. ...
7
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243 views

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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3answers
290 views

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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1answer
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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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Why are alkali basalts found at rifting centres and on top of 'plumes', whereas MORBs are generally tholeiitic?

So I was essentially wondering why it was that the basalts on top of 'plumes' at 'hotspots' (sometimes called OIBs, ocean island basalts) and at continental rifting centres are enriched in alkaline ...
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What lithologies are deemed most suitable for the storage of nuclear waste

I have visited storage- and test facilities that are within salt and clay (Opalinuston) lithologies. What are other lithologies that are considered for the storage of nuclear waste and what are their ...
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Is angular momentum preserved in a gastropod fossil?

In the Northern hemisphere the rotation of the Earth determines a counter-clockwise spin on matter. Weather, ocean currents all are related in that spin. I wonder if my snail fossils preserve the ...
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1answer
8k views

How much of a mountain is below the surface?

Is there some kind of math rule for how much does a mountain extend (depth) below the surface? I found an article like this http://www.livescience.com/6595-depth-himalayan-mountain-roots-revealed....
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1answer
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Is there geological evidence that the moon once collided with the Earth?

I've seen models in astronomy that show how the Earth-Moon system must have come together after a collision. However, I have not heard whether there is any actual physical evidence on Earth that ...
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viable geothermal energy supply from exhausted fracked gas wells?

The UK legislator with primary responsibility for energy has claimed that exhausted fracked natural-gas wells will be suitable for re-use as a geothermal energy supply (not necessarily geothermal for ...
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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 ...
11
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1answer
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How can scientists be confident of isotope ratios in past eras and varied locations, used for radiometric dating?

Radiometric dating relies on past isotope ratio predictions being very reliable. However, this is not necessarily so. For example, in Uranium forensics, 235U and 238U ratios are about the same for ...
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591 views

Why are minerals found in “large” quantities and not scattered throughout the earth as individual atoms?

Heavier elements are created in stars. After stars die they scatter these heavier elements throughout the universe. These elements eventually gather to form planets. But why do we find "chunks" of ...
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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 ...
6
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1answer
110 views

Would it be wise to monitor real time human activity to anticipate earthquakes?

Documented strange behaviors of animals before an earthquake could invite us to believe that some of them anticipate tectonic activity. We also know that human complex organization makes it difficult ...
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747 views

What is this Cape Breton rock?

What is this rock? I found it in Cape Breton, Canada
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1answer
1k views

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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1answer
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What kind of coal did I find?

I found a piece of (what I believe is) coal, on Cape Cod last week. Its density is 1.43 grams per milliliter. With this information is it possible to know whether it's Anthracite, Bituminous or ...
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1answer
3k views

How much fossil fuel came from the Carboniferous?

It is said that most of the fossil fuels in existence today (coal, oil, gas) came from the Carboniferous period. A unique set of circumstances lead to the creation of fossil fuels, which depends on ...
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217 views

How are the patterns in solid rock born

I took this photo on my vacation in Finland showing white stripes in the rock going different ways. How are these patterns born?
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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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2answers
251 views

How to determine how long ago a rock was broken?

I know that there are techniques that help scientists determine the age of a rock. But is it also possible to determine how long ago a rock was broken? For example, how could we date the formation of ...
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1answer
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Determining a rock age using volcanic ash layer

I wanted to know if volcanic ash deposits found in the geologic record are most useful in correlating the age of rock layers if the volcanic ash was distributed over a large area during a short period ...
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1answer
536 views

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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1answer
312 views

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 ...
14
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1answer
117 views

In what sense did the Oklo reactor “trap” its own nuclear waste?

A number of popular writings on the natural fission reactor at Oklo, Gabon (e.g. here) state that some of the energetic byproducts (krypton and xenon, presumably 85Kr and 133Xe) of the reactor were "...
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1answer
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How can I tell if a rock is really petrified wood?

I found a rock in the Mojave desert and it resembles a tree branch including what appears to be wood grain. Is there some test or observation that can be done at home to conclusively answer my ...
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156 views

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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1answer
117 views

Why would a suite of related rocks have one anomalous sample?

I have a suite of rocks that have nearly identical major element chemistry, but a single sample has quite different trace element concentrations. All the rocks are trachydacites. I know the analysis ...
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1answer
2k views

Is there any correlation between La Niña/El Niño and seismic activity?

I've read in the past that extreme precipitation levels may have an effect on seismic activity, and wondered if anyone has ever analysed the La Niña / El Niño cycles to see if there are any ...
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1answer
221 views

Are there situations where the groundwater table doesn't follow the morphology of the surface?

In most or all geological site reports I read, the groundwater table (of the uppermost groundwater layer) always followed the morphology of the surface. Is this always the case? Are there signs for ...
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1answer
232 views

How to interpret the use of late and early Tertiary from older literature?

When reading older papers how should I interpret the use of "Late Tertiary" and "Early Tertiary"? Would these periods equate to Paleogene and Neogene, or was there a different accepted boundary age ...
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1answer
206 views

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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2answers
709 views

What is a good definition of the word “rock” for teaching?

Note that it needs to include coal and chert, therefore the common answer "a rock is made of minerals" is incomplete.
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What made the Grand Canyon the “greatest” canyon in the world [closed]

The Grand Canyon is nearly 446 km (300 miles) long, 29 km (18 miles) wide, and over 1,8 km (1 mile) deep. To the best of my knowledge, there is no other canyon of comparable size in the world. Is ...
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1answer
591 views

What is the origin of the Montmartre mountain in Paris?

I have always wondered what is the origin of Montmartre mountain in Paris. What surprises me is that the whole area seems quite flat, and yet there's a very steep hill in the middle. How has that ...
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1answer
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What causes “hydrocarbons” to take the form of petroleum versus natural gas?

"Hydrocarbons" are found in geological formations consisting of strata or layers of rocks. Specifically, they are formed from decomposed organic material (that contains carbon), that bonds with ...