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 separates the Karakoram Range, the Hindu Kush, and the Himalayan Range?

In Google Maps, I don't see any boundary between the Karakoram (a.k.a. Karakorum) Range, the Hindu Kush, and the Himalayan Range. What separates these ranges?
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How did the terms “acidic” and “basic” come to be associated with $SiO_2$ in igneous rocks?

Students of geology are introduced to in their petrology course, (or used to be), to the terms "acidic", "basic", and the associated term "intermediate" in relation to %$SiО­­­_{2}$ in igneous rocks, ...
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Is there a list of instances where mountains that have been mined out of existence?

Reading the Wikipedia entry for the Australian town of Broken Hill, I came across the following piece of trivia (emphasis mine): The "broken hill" that gave its name to Broken Hill actually ...
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Methods and Software for Interpolating/Modelling of Stratigraphic Well Data in 2D/3D

I have some geologic well data. The lithologies have been interpreted, and stratigraphic columns have been drawn. The columns have been adjusted for elevation, and correlation has been done between ...
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Why do we measure eustatic sea-level from the center of earth?

Earth is rotating so it has a ellipsoidal shape. The measurement will therefore be different from equator and pole. So why do we measure eustatic sea-level from the center of earth?
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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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What was the likely composition of Earth's early crust (how did crustal composition evolve)?

Was the first crust entirely mafic (oceanic) crust which was later distilled via volcanic arcs along subduction zones to make felsic rocks or did the earth start with bits of felsic crust? Are the ...
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Maps and Faults

I'm having trouble determining the type of fault represented on this map. What type of fault is represented on this map? What is the fault orientation? What does this mean?, Do I do this by working ...
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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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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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Geological evidence about climate change: has there ever been a period with a rate of climate change as great as it is today?

Most statistics about climate change are based on climate data over the last 150 year (as long as records have been kept). This seems irrelevant in terms of the geological time scale of temperature ...
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How are deposits of metals like tantalum located?

I am curious of how metal deposits are located in general, but to keep my question focused I wanted to just ask about tantalum for example. Are there people who traverse their own country drilling ...
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Historically, how did the total amount of salt / NaCl on Earth develop?

After reading this question about the origin of NaCl on Earth, I'm wondering: How did the amount of NaCl develop historically? Is it a more or less linear growth until today? Was it such a linear ...
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Why are most minerals so rare?

There are 4,660 known minerals, so why are most of them so rare? Is it to do with the structure of minerals?
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Actual thickness of permafrost vs theoretical maximum possibly permafrost thickness

I came across a question in my notes about why the actual thickness of permafrost is much less than the theoretical maximum possible permafrost thickness value. The actual permafrost measure on sites ...
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How was Nastapoka arc formed?

As wikipedia says, the Nastapoka arc is a geological feature located on the southeastern shore of Hudson Bay, Canada. (Other description with picture at the Royal Astronomical Society of Canada) No ...
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Mars maar craters explosive style formation gravitational effect

"Maars usually form when magma rises within a fissure and interacts with groundwater. If groundwater ceases to interact with magma at times during the eruption, continued magma ascent to the surface ...
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Is there a widely accepted reason for the formation of tafoni?

Expansion of tafoni seems to be based on weathering (seems reasonable enough.) But what creates them in the first place? There are a number of explanations online (Wikipedia lists eight plausible ...
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Identify yellow-tinted translucent mineral

I found a mineral near the hexagonal rock formations in High Island, Hong Kong that I'd like to get ID'd. It has a greasy and subadamantine lustre. It can scratch a U.S. Quarter Dollar and some types ...
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What is the metamorphic field gradient useful for?

As I understand it, the metamorphic field gradient is the PT line traced out by the maximum temperature points of a series of PTt paths of rocks from the same metamorphic event. What exactly is this ...
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High-resolution laterolog array tool

Does anybody know if it is necessary to apply corrections to the reading given by this logging tool? Corrections such as bed thickness, borehole diameter, invasion, etc.? If so, is there anywhere I ...
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Did an impact crater cause the formation of the gas fields in north eastern South Australia

In the paper High Impact Reservoirs, the authors claim that impact craters have lead to both the creation and destruction of petroleum source rocks, reservoirs and traps. Recently it was announced ...
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Age of fossils found in rocks

I have heard the claim by creationists that geologists date rocks by the fossils they contain and date fossils by the rocks in which they are found. This supposedly invalidates radiometric ages ...
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What keeps water from sinking into earth?

I remember reading somewhere that there's evidence of water on Mars but it all sank into the Martian soil. So what prevents that happening on earth? Some people say it's because the crust is not ...
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Megathrust earthquakes on subduction zones

I am a beginner in geology and earthquake studies, and learning about subduction zones recently. Question is: do large earthquakes (sometimes referred to as megathrust quakes) occur on any point in ...
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Why is my ♦ hammer (i.e. diamond) so durable, but it can burn? [closed]

For those confused about the title, there's a joke that every moderator has a "diamond hammer" (diamond from the little by the username). In a chat discussion, it ...
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Why silicon is abundant in earth surface?

What is the reason for having silicon in so large quantity on earth surface?
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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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Why does NW coast of Scotland look like it does? (Similar to Norway, so different to other European coastlines)

When looking at a map of Europe, I always wonder why the North-West coast of Scotland has a very similar craggy outline to the NW coast of Norway. It is completely different to the smooth outline of ...
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What type of rock is this that is light colored with greenish crystals?

I found this rock. It is probably a very common rock but could an expert please tell me what rock this is?
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Is there a difference between Density and Specific Gravity?

My textbook says that the specific gravity is "the ratio of the mass of a mineral compared with the mass of an equal volume of water." Is this any different to density? If so, how? If not, why does ...
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What would change if our earth lacks mountains?

I just asked myself what is the role of the mountains on our planet earth? Well there's a well known role for the climate and weather. But is there a kind of physical or geological role? What would ...
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Is an underground mine collapse or a tunnel collapse called a sinkhole?

Imagine there's an underground man made structure e.g. a tunnel or an underground train station that collapses creating a depression in the surface. Would that technically be called a sinkhole? What ...
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What are the cubic formations found inside Larimar gemstones?

I recently noticed what appears to be common cubic formations just beneath the surface of Pectolite (Larimar) gemstones. They quite resemble transparent sugar sprinkles. Each formation isn't perfectly ...
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Is this iron ore? If so what kind? And is it naturally deposited in texhoma?

It's completely hollow on the inside and looks like a bubble while layered on the outside. Slightly rusted.
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Making a local geological field trip an interesting and educational event for children?

I have no expertise in geology or earth science, but I would like to do a "field trip" with my home-schooled young children (under age 10) where I could teach them about geology from a hands-on ...
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Can soil color give accurate data about properties which affect it?

I understand that soil color is affected by several factors some of which are (but not limited to): organic matter content underlying parent material drainage and aeration Soil color being an ...
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Can we see lava in a divergent tectonic boundary?

Can we actually see an orange line of lava if we look down to the crack of the divergent boundary of tectonic plates?
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Determining hardness using teeth

So I know scratch tests are pretty common to quickly get an estimate of a rocks hardness. Also tooth enamel is a common material with a 5 on mohs scale. So far so good, but what shocked me is that I ...
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What is the motivation behind the choice of unglazed Porcelain as a Streak plate?

What characteristics does Porcelain possess that makes it a good choice for the Streak test? Additionally, are there any other materials that could also be used for designing a Streak plate?
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How does quartz form in calcite veins?

This question might be a bit silly, but I have to ask since I am very curious and I did not find any good answer. I visited two places, where quartz crystals (var. smoky quartz) occurs - and both ...
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What is the CI chondrite concentration of REEs/rare metals, in ppm/grams per ton?

I am researching the abundances of rare earth elements and rare metals in meteorite samples, because I want to investigate the notion that asteroids represent abundant stocks of rare resources. The ...
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Have the landmasses of North and South America ever been part of the same continent?

I know this question have been asked very often, but I could not find a proper answer around StackExchange, so I thought this might be a good place to ask: Have the landmasses of North and South ...
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What would the geology and climate of a supposed landmass near the pole be like, assuming a thoroughly warmer planet? [closed]

I am designing a fantasy setting for pen-and-paper role-playing (and potential novel) purposes. I have decided that a continent be situated right on a Pole of some imaginary planet with axial tilt ...
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Identification of limestone type

These are images of a stone found and used extensively in the Jammu & Kashmir region between India and Pakistan. These are called devir or devri in the local parlance. Following is the ...
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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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Geology - Rock Identification help please. Melted metal looking rocks in the middle of nowhere

I know nothing about rocks. But I found this and a bunch more that are similar hiking up a river in the jungle of Laos, in SE Asia. If anyone could help me ID it hat would be awesome because we are ...
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Pigments from earth

We're about to do lime wash on one of our heritage buildings. We decided to use ochre as pigment because it comes from earth. My boss says with any pigment that comes from earth, we don't need to ...
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What is a “show” in petroleum geology?

Is a show when naturally ocurring oil seeps out of a fracture on the surface? Or is it when engineers fracture rocks in order to extract oil?
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How does Vertical Electrical Sounding Work?

I recently conducted a brief training exercise with VES equipment, although it had to be called off due to rain. I can't help but wonder about the basic physics of it, why is it that increased ...