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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How plausible is it that "a portion of the ocean's floor" could suddenly be "thrown up to the surface" as described in this Lovecraft story?

This question came to me after reading H.P. Lovecraft's "Dagon"- the protagonist has fallen asleep drifting on the ocean in a small boat. He wakes up one morning to discover he's been ...
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The problem of the dissimilarity in the range of data values ​between the gridded data and the channel database in geosoft

My question is about the problem when displaying the eU radiometric map of my study area, as the range of values ​​for the eU map is much larger than the actual range values ​​of the eU channel in the ...
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1 vote
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What is the history behind the present day geology of California? What processes took place that led to the formation of each region as shown in fig?

This is the image showing the different geomorphic provinces of California. What led to the formation of these provinces, and what events took place that resulted in the diverse geological setting of ...
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3 votes
1 answer
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For how long can mid-oceanic islands be volcanically active?

The island of St Helena in the South Atlantic was volcanically active for 5 million years, or maybe longer. Is this period of time unusual - which other mid-oceanic islands were active for as long as ...
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Does the collision of India influence the geology and geography of some of the other mountains of Asia, or just the Himalayas and Tibet?

This here is a nice and lovely map of Asia. Note that the teardrop-shaped Tibetan Plateau dominates the map, and we have India to thank. For the last 50 million years, it has been pushing upwards, ...
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2 votes
0 answers
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Coastal Hill Formation (Valparaíso, Chile)

This seems like a simple question, but I can't find much information on the web about this, and I haven't studied Geology or Geophysics. In Valparaíso there are a large number of "Cerros" (&...
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3 votes
0 answers
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Patterns on Basalt

These Basalt rocks were hand cracked and used to build the walls on my home. Many of these rocks have these semi circular pattern, made of the basalt itself. It's just a bit darker than the rest of ...
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1 vote
0 answers
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How should we deal with geochemical anomalies in stream sediment?

We know that geochemical anomalies in stream sediment usually distributed along the drainage. Therefore, when we use stream sediment as the sampling medium and found an anomaly, we should trace the ...
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0 votes
1 answer
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In Geology - True Dip versus Apparent Dip: When dip is estimated along a line of section, how is that dip determined in relation to true dip?

The map presents a summary example of topography and mapped units X and Y. From the information presented, can someone help me determine or estimate the actual dip along the line of section, A-A'? I ...
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3 votes
1 answer
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How these rock features form?

I was walking on a reef in northern Italy near Genoa. (44.3230136N, 9.1462828E) The rock was composed of rocks of varying sizes, colors and shapes held together by some kind of a seemignly softer ...
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8 votes
1 answer
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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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5 votes
0 answers
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What is causing the crustal extension exhibited by the Basin and Range province in western North America?

Is there any link with the subduction of the Farallon Plate and the associated spreading center?
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1 vote
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Would 2 continental landmasses at a divergent boundary (i.e. Africa and S/A) stop/reverse direction if a continent overrode the original rift?

Something that's been bugging me for some time now. If, for example, Antarctica started subducting in the direction of the Atlantic Ocean (I'm aware it's not and isn't predicted to), and began ...
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3 votes
2 answers
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Can continental plates collide and fuse together without an orogenic band or magmatic arc or at the junction?

I have seen this diagram on Wikipedia (link below). It shows that some North American mini-plate boundaries are orogenic bands and some are magmatic arcs, and I think those correspond to continent/...
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3 votes
0 answers
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Why is the Colorado Plateau so stable?

The Colorado Plateau somehow has avoided all the tectonic activity around it over hundreds of millions of years. Is it just luck, or is there something about that chunk of crust? I have toured the ...
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2 votes
1 answer
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What are the prerequisites for petroleum geology?

I'm in my late thirties and decided to get back to studying. I want to learn petroleum geology but it's been 10 years since I last opened any book, so I basically forgot tons of stuff that I learnt. I ...
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2 votes
1 answer
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Difference between crystal and mineral

What is the exact difference between a crystal and a mineral?
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1 vote
0 answers
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Igneous and Sedimentary Rocks' Susceptibility to landslide

Which is more susceptible to landslide based on lithology compared to one another? Granite, Conglomerate, Sandstone, Mudstone I've been tasked to create a hazard map and was given a Geologic Map, ...
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8 votes
1 answer
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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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5 votes
1 answer
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I am searching for a word to describe the area of a glacial valley where the sides transition into the floor?

I have been tasked with proof reading before publication a Russian paper that has been translated into basic English and am searching for a word to describe the area of a glacial valley where the ...
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3 votes
2 answers
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Why is felsic (granitic) lava so much more viscous when flowing (or trying to) than mafic (basaltic) lava?

A lower average temperature is, apparently, only part of the answer.... Several sites said composition, not temperature, explains most of the difference... And the difference in viscosity can be up to ...
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2 votes
2 answers
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Why is the inner core about 85% iron and the rest (mostly) nickel, while the outer is roughly 80%/20%, if nickel is denser than iron?

As stated above.... I really cannot think of a good reason, on my own, why this should be so.... Is it a mystery to geologists?
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4 votes
1 answer
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Can paleomagnetic techniques determine the exact direction of Earth's magnetic poles in the past, not just their polarity?

Since our planet's magnetic poles are not usually, precisely, lined up with the geographic poles of Earth's axis, and since they move around a lot, can paleomagneticists (is that a word?) determine ...
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3 votes
2 answers
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Geodes that float in the ocean?

What would happen if you threw a geode into the ocean. Would it sink down to a certain altitude based on how hollow the geode is or would it float on top or sink to the bottom? And could geodes form ...
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3 votes
1 answer
60 views

Elevation accuracy to distinguish maximal gravity anomaly of a sphere with 50% hematite

Question: What is the accuracy required in elevation to distinguish the maximal gravity anomaly of a spherical 50% Haematite (Iron mineral) ore with a radius of <...
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4 votes
1 answer
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Is there any mineral that survives hard degree metamorphism?

When a protolith enters in metamorphism, the minerals transform in other new stable minerals while the pressure and/or temperature increase. Is there any mineral that would not be affected by a high ...
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0 votes
1 answer
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What characteristics are considered when distinguishing a place based on physiographic provinces?

Wikipedia describes a concept called "physiographic provinces". If I understand right, geologists simply created lines on a map, to create clusters of places that are geologically similar. ...
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8 votes
3 answers
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What gases are in the vesicles of pumice?

Many references state that pumice is formed by gases in lava, but I have yet to find a reference of which gases they are. If a piece of pumice floats, then conceivably it still contains the original ...
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1 vote
1 answer
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How to genetically classify a weathering mineral or a mineral formed in soil?

Coming from this question and the answer, a proposed genetic classification of minerals: Endogenic: Magmatic, Metamorphic, Hydrothermal. Exogenic: Supergene, Sedimentary. My question is how would ...
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2 votes
1 answer
100 views

Are carbonated stalactite deposits sedimentary deposits?

Acording to britanica.com: sedimentary rock, rock formed at or near Earth’s surface by the accumulation and lithification of sediment (detrital rock) or by the precipitation from solution at normal ...
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3 votes
1 answer
56 views

What questions to ask to students from a mineral guide dataset?

I am programming an app that consist in 180 mineral sheets of interest for geology students. My database have the following fileds: Identifier Name Name 2 Type Class Formula System Environment1 ...
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13 votes
3 answers
14k views

If the Bennu asteroid were to hit within a 500 mile radius of Yellowstone National Park, will it trigger a super volcano at Yellowstone?

I am curious to know if it would be highly probable that if the Bennu asteroid were to hit the Earth in 2182, and the point of impact is within a 500 mile radius of Yellowstone National Park, will it ...
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5 votes
2 answers
659 views

Python - How to write interpolated raster to netcdf file

Currently i am dealing with a bunch of coordinates (epsg:4326 => lat/lon) and their corresponding value (temperature). The goal is to write these coordinates and their values into a simple netcdf ...
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1 vote
0 answers
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Oil FIlled Geode

Five weeks ago my dad and I collected geodes near Bedford, Indiana, from private property with the full permission of the owner. While cutting the rocks one produced an unexpected result - oil poured ...
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7 votes
0 answers
102 views

Volcanic Explosivity Index of Cumbre Vieja eruption

I have been following the last events of Cumbre Vieja eruption since it started last month. Trying to grasp some basic knowledge of volcanology I have seen the eruption is classified as VEI-3 in the ...
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7 votes
2 answers
161 views

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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1 vote
0 answers
66 views

How was the Mozambique Belt formed

I'm looking for some of the most comprehensive or significant articles on the Mozambique Belt in East Africa. If anyone can recommend some specific papers regarding the Geological history of the belt ...
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3 votes
0 answers
125 views

Is Radiocarbon dating flawed?

I posted this before on physics stack exchange, but it was deemed off topic, which is understandable, so I hope it won't be here. Recently, I stumbled upon an article by an individual named A.M. ...
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3 votes
2 answers
87 views

When did the proto-Himalayas become non-volcanic?

In the normal course of events, when continents move toward each other, at least one coast will be associated with a subduction zone and corresponding volcanic activity. When the Indian subcontinent ...
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2 votes
3 answers
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What methods/apparatus are used to model the early Earth? What do we know of their accuracy?

A friend of mine asked our teacher but the class was over and in online mode, I can't ask my teacher until the next lecture. It sparked my curiosity, I know we use carbon dating for finding the age of ...
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4 votes
1 answer
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Generalized Soil Unit Information on Soil Characteristics of FAO/UNESCO Soil Map

I have some doubts regarding the FAO/UNESCO Soil Map of the World. I have downloaded the ESRI shapefile format of Digital Soil Map of the World (3rd download link on this page). Among other files, ...
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5 votes
0 answers
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Can geochemical anomalies of stream sediment samples be used directly for mapping targets?

We know that geochemical dispersion in stream sediment is much widespread, facilitating discovering mineral targets in a regional scale. However, we also know that there should be discrepancy in space ...
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1 vote
2 answers
85 views

Isotopic dating of metamorphic rocks

I read in my physical geology textbook that sedimentary rocks cannot be dated using isotopic dating, because they are formed from fragments of other rocks and minerals, which if you were the subject ...
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4 votes
1 answer
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Why were Fe-oxides not usually used for finding skarn Fe ore deposits in geochemical exploration?

I found that Fe-oxides were usually not used for vectoring Fe mineral deposits of skarn type in geochemical exploration. As an indicator element, the common practice told us Fe-oxides should be the ...
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0 votes
1 answer
42 views

What are some effective approaches to enhancing fossils in amateur found rocks?

My stepson found this rock on the shore of Lake Michigan and gave it to my son who loves fossils. I'd like to really bring out those fossils. What are some techniques that I can try that won't ...
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3 votes
0 answers
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Water flows under the headwater and soil liquefaction has formed

A retaining wall 40 cm thick with variable height (thin-walled corner) is being built in the mountainous area. At the time of the geotechnical survey and design, there was no reservoir next to the ...
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1 vote
1 answer
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How did these holes form in the rock? [closed]

I've been trying to figure out how these holes formed in the rock. These pictures were taken in Quebec, Canada on small lake in cottage country. The strange thing is that they are almost both ...
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4 votes
1 answer
576 views

What affects where a terrain will be rocky or grassy?

I’m working on a terrain generator and I now need to color the terrain to be rock, grass, or snow. Ignoring snow for now, at first I thought I’d make flatter areas grass and make steeper areas rock. ...
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4 votes
1 answer
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Did geologists determine the age of rocks and fossils before the advent of modern scientific dating methods?

Did geologists determine the age of rocks and fossils before the advent of modern scientific dating methods such as radiometric, electron spin resonance and thermoluminescence? If they did, does ...
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14 votes
4 answers
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What is the pressure at the center of the Earth?

In the question Does gravity increase the closer to the core you get?, it was determined that gravity reduces to zero at the center of the Earth. That is logical. However if pressure is proportional ...
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