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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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Peninsula vs Cape

I know that Peninsula is much larger than a cape, but is there a definite way to differentiate them? I.e. by area- if the total area is larger than 30 sqkm, any headland is classified as peninsula..
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what kind of rock is this? soo strange

What is this? this rock is so strange. White inside but was encased with something greenish brown.
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I found this small round heavy rock in a box of my dad’s old army stuff [on hold]

I found this seavy black silvery rock found in a box of my dad’s old army stuff. He was stationed in Arizona sometime in the 50’s. Not sure if it’s from there or just happened to be in that box.
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Why can't we dig deeper?

I recently read on another SE site that there's a limitation on how deep we can dig into the earth. A Google search reveals that temperature is the problem. I quote from a Popular Mechanics article ...
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Help identify my rock please? [on hold]

found this in the backyard, any ideas which type it is?
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1answer
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UK Mineral identification help

Can anyone help me identify these minerals please? I found them on a beach in northern England. The first has tiny angular crystals, some slightly pinkish maybe in certain lighting conditions but grey ...
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Can you please help me to identify this thing I found inside a rock in the Almanzora riverbed Spain

Can someone please help me identify this thing I found inside a rock in the Almanzora riverbed Spain
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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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What is an inversion

What is an inversion? What happens to the sediment in between? I understand that as the crusts move together a bulging appears.
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Is sterescope still used to do cartography with orthophotography?

I used this tool at my degree a couple of lusters ago to do cartography with aerial orthophotos. We used it on cartography and geomorphology subjets. Source: gumtree.com The method consists ...
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Can anyone tell me what this is [closed]

Not sure what this is found in Oklahoma
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37 views

what type of rock is this? blue/green and brown [closed]

I found this rock while up in the mountains and I have no idea what type of rock it is.
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Assessing graded bedding in metamorphosed pelitic sediments

I have the following image of metasedimentary outcrop from a Proterozoic continental rift-fill sequence: The middle layer has a pelitic composition and contains abundant cordierite porphyroblasts (...
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Is this a geode?

So just having issues with identification looks like a outer line of rock a bit transparent but the inside polished looks waxy other side of stone a bit more foggy but still blue visible Edit - ...
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What is this heavy green rock?

I found this grenish rock at a beach in Northwest Ireland called Inishcrone. It measures 45mmx35mmx22mm. It weighs 57 grams and has a density of 2.90. It is opaque, does not attract a magnet. It ...
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1answer
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What is this heavy, dark grey and almost round rock?

I found this 'rock' on the beach in North West Washington State. It's almost perfectly round save for a few bumps, it's dark grey in colour, solid, feels smooth like any stone you'd find on the beach,...
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How much hydrogen can be extracted from the deep continental crust?

Far below the earth's surface, hydrogen gas is continuously produced through serpentinization. At least some fraction of this hydrogen remains trapped in the deep continental crust; indeed, Soviet ...
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What leads to formation of a nonassociative gas reservoir?

Why in some cases natural gas occurs in association with oil (associated gas) and in others there is no oil (nonassociated gas)? Is it because of the type of the rock? Or is it the pressure/...
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Can someone help ID this rock

Found today in a creek in Indiana, has a geode look and the broken edge shows red opaque facades.
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Identification required, rock formation found whilst on holiday in Cephalonia, Greece white object embedded inside?

This rock was found in kephalonia Greece, on a beach in lassi. The rock is black in colour, smooth with thumb like prints, very metallic smell and very slightly magnetic. We took this rock to oxford ...
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1answer
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Which ocean is going to be swallowed by the Supercontinent Cycle, Atlantic or Pacific?

The register shows several supercontinents have been formed on Earth's History: "The most recent supercontinent, Pangaea, formed about 300 million years ago (0.3 Ga). There are two different ...
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1answer
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could a rhyolitic magma melt a ferromagnesian mineral like olivine?

if the temperature of a felsic magma is about 800-650 °C and olivine melting point oscillates between end members forsterite and fayalite near 1900-1200 °C, Does this mean that an olivine crystal in ...
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2answers
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Can anyone help me identify this type of translucent green mineral? [closed]

This is the photo of the rock. I found it in the mountains in yemen, near rocks where a well was dug out. Its translucent green and It doesn't feel that heavy. I think it's some type of quartz.
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1answer
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Why doesn't Earth absorb our carbon emissions?

If we look at the carbon cycle, we see that man-made carbon emission only account for a tiny fraction of all $\text{CO}_2$ emissions. However, we see a steady rise in atmospheric $\text{CO}_2$-levels....
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Is there a name for subduction boundaries at the North of Australia?

I know the ridge at the South of Australia is named Southeast Indian Ridge. I would like to know if there is a geological name for the three subduction branches that cross indonesian zone, at the ...
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What are the farthest Time Zone locations? [closed]

What place in the world has the farthest time zone? I heard it was Kiribati but then I found that Apia (Samoa) is further. So, is there anyplace that is the farthest in time than these two? What about ...
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1answer
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How can I identify “tough” (mixed) granites?

I am trying to parse an old geologic description of stone suitable for use as road metal: Care must be taken to distinguish the difference between the hardness of a stone and its toughness......
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Artifact? Found in US North Carolina close to Morrow Mountain State park [closed]

Scale in inches. I found this in a river. One surface of it (narrow surface) is so flat that I couldn’t quit looking at this find.
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2answers
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Can gemstones be cut into sheets? [closed]

TL;DR: Without lasers, electricity, or otherwise modern tools, could large transparent gems be sliced (like glass window)? So I’m world building. On this planet they have caves with enormous gemstone/...
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421 views

What is the basis for the Geologic Time Scale

The Geologic time scale was completed in the mid to late 1800s. What methods were used to date the various subdivisions?
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Is this Dragon Jasper?

Bought these rocks at a shop they were selling as Dragon Jasper,but when I density tested them they were 3.09 which I thought was a bit high for Jasper, and generally Dragon Jasper has Deep red veins, ...
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1answer
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An oblique-square-prism crystal?

Does any mineral crystallize in the shape of an oblique square prism? If so, what crystal system (monoclinic, cubic, hexagonal, etc.) would such a mineral fall under?
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1answer
44 views

Is this an agate? [closed]

So I have found these in a creek there are some that look like this and I have broke them open and they were full of crystals these seem to small and I have tried cracking then and they wont budge I ...
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0answers
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Did low $\small\sf{CO_2}$ levels affected Permo-Triassic mass extinction?

After answering this question: How did plants adapt to $\small\sf{CO_2}$ levels past 400k years? Why won't they do it again? I know Permo-Triassic mass extinction is associated to a catastrophic ...
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How Big Were the Siberian Traps ORIGINALLY?

252 million years ago, Siberia was subject to a mass series of flood basalt eruptions, creating a large igneous province called the Siberian Traps. Today, it measures 2.7 million square miles in area ...
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What is an isolated land area of one type of rock surrounded by land of a differing rock type called?

For example, if there were a large land area with exposed basalt, in the middle of which is a smaller isolated patch of Granite, what is that isolated patch called? I came across the single-word ...
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I found this rock on my property years ago and was curious what it was [closed]

What kind of rock is this? I found it on my property a long time ago and I can pinpoint exactly what. I was thinking red jasper maybe?
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1answer
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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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1answer
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Could this rock be Basalt?

This rock is 2 3/8", weighs 71 grams has a density of 2.958,I tested the density a few times and its always 2.958, has a hardness of 6-7 almost clear streak test, I tested the streak again and I would ...
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3answers
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Would oceans regenerate if removed?

On Earth, there is enough Hydrogen and Oxygen to make 13,88 million km$^3$ of water (calculation below). However, oceans contain only a tenth of that. Clearly, most of the hydrogen must be stored in ...
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1answer
104 views

Are we at the beginning of a Heinrich Event?

Does our current weather trend properly reflect a Heinrich Event? It seems like the drastic weather swings are what I would expect but I realize that is not definitive. I don't see the term bandied ...
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1answer
151 views

What is this green yellow heavy stone?

no known origin,its opaque its 2 1/4" leaves no streak, has a hardness of 6-6 1/2 I drilled it with a diamond plated bit,it is a very tough stone.It weighs 2ozs 56.6 grams.When I drilled it the powder ...
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1answer
120 views

What kind of lava tube feature is Cleopatra's Grave?

Cleopatra's Grave is a natural feature inside (warning: PDF) Catacombs Cave in Lava Beds National Monument near Modoc, California. Source: LookBeforeYouLive My apologies, as this image is somehow in ...
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1answer
61 views

Help identify my redbrown rock with crystal like formation on the inside

This rock is red/orange/brown in color. It is slightly clear/translucent when held up to light. Will not scratch with a knife. Has a crystal like structure on the inside.
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1answer
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What is the difference between subvolcanic rocks and plutonic rocks?

I'm studying Plutonic (Intrusive) rocks and i really dont understand the difference between PLutonic Rocks that form in Sills and Dikes from the so called subvolcanic rocks, also known as a ...
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1answer
130 views

Please Help Identify My Rock

This rock is smooth, heavy and dark grey/black in color with white blotches which are different in shape and size and are also porous. It scratches by a knife and I found it in with many pails of ...
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1answer
242 views

How do you tell if smoky quartz has been irradiated?

I want to purchase a piece of smoky quartz crystal, but am not sure if it is irradiated. Is there a way to tell if it has been irradiated? Thank you.
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1answer
77 views

Can someone identify this mineral? [closed]

I found this in a stream in Medicine Bow-Routt National Forest, Wyoming. One side (2/3 length) has a pointy pyramid with four faces; other side (1/3 length) has four faces but with with an edge ...
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0answers
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How do people determine initial ratio of the parent nuclide and daughter product in radiometric dating?

I understand that we have zircon crystals that prevent entering or leaving of nuclide or lead after forming. But how cand we understand what was the initial ratio?