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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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Found a white, glittery rock in the woods of ILLINOIS. MAY YOU PLEASE HELP ME IDENTIFY WHAT KIND OF ROCK I'VE FOUND?

Its mostly white, kind of grayish but not really. And it has little particles or minerals that make it look really glittery. Im really hoping its some type of quartz rock or it at least has quartz in ...
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What kind of rock/fossil is this

I found it in the clay in seattle, wa. It started out looking like green grey concrete, but I broke a piece off and noticed blue, so I soaked in hydrochloric acid for two days periodically cleaning ...
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1answer
20 views

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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Please help me identify this rock. Thanks! [on hold]

I found this rock in our home and I was curious, about the type and background of the rock. We live in the Midwest. Any information would be greatly appreciated.
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I found a large 3925lb rock [on hold]

It,s almost totally round a little Oval shape. It's close to old volcano's I did weight it and it weight's 3925 lbs, it's about 3 ft tall There was another one found in the same area I was ...
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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? [on hold]

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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How to determine the strike and dip from apparent dip?

I've used a stereonet to plot a line striking 065 degrees and dipping 20 degrees NW. The pitch given to me is 40 degrees which I've also plotted. it proceeds to say "on a vertical canyon wall ...
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1answer
120 views

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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Geology - Approximating Earthquake Intensity Radius Decay

McCue's formula ( $Rp = e^{\frac{MI}{1.01}-0.13} $) lets us, in a very crude approximation, assess an earthquake's intensity radius. However, I cannot find a formula which expresses this radius decay, ...
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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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Hi! Can anyone help me to find what type of rock this might be

Hello, this rock was found on a hike near a stream of water at Eaton Canyon in Altadena, California. The rock seems to be made of layers that when hit against the concrete floor will break apart into ...
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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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1answer
219 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
43 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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1answer
101 views

Can someone please help me identify my rock?

I found this rock under water over 20 years ago while swimming in Lake Huron near Kincardine, Ontario. It’s a little smaller than a baseball although it is very dense and a lot heavier than it looks. ...
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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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1answer
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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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1answer
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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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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
77 views

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
101 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
139 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
106 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
60 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
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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
155 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
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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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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?
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1answer
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Geological Differentiation: variables and size requirement

Geological/Planetary differentiation is one of those topics that gets glossed over in intro Geo courses. We know that differentiation occurs over deep time (and will never end) and is a result of the ...
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1answer
341 views

What is this yellow stone

I found this yellow stone in a creek.It was easy to break by slamming it against another stone and has evenly spaced crystal clear grains.They are very clear that under the sun I thought that water ...
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1answer
87 views

Mineral identification - please help!

I'm currently writing an essay on a mosaic in the British Museum, and am unsure about which stone the frame is constructed from (pictured). I would be most grateful for help identifying it. Thanks! ...
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1answer
60 views

Sink holes in drainage area

I live in Florida (aka the land of sink holes). Due to the flat nature of my area, it is common place for housing developments (and any developments really) to dig large drainage areas to give water ...
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1answer
131 views

Is this a gold ore? I found it in a California creek next to a mountainside

I found this rock while hiking in a creek. It has some bits of white quartz, sheen and some brownish coloring. Does anyone know what it could be? Is there any possibility that it might be gold ore? ...
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1answer
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What is this translucent and blue vein crystal, 7.5 < Mohs < 9, Lustre: Aventurescence

It looks like quartz, but it has blue veins on the surface that look died. Not all surface scratches are blue though. Hardness: > 6.5. Nail file will not scratch it. > 7 quartz will not scratch it. >...
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1answer
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What is this translucent blue-green oblong crystal?

I think it might be aventurine of some sort, but I'm not sure. Hardness: It is harder than a steel nail file. The file leaves a track, but it rubs off, leaving no mark. I scraped it on the bottom ...
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1answer
58 views

How do we detect floods?

How do we know that there was a flood at a certain place at a certain time. For example if there was a flood in place A 200 years ago. How could we detect it?
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1answer
57 views

What type of rock is this? Help [closed]

Please help me identify this rock. I’ve found it in a cave.
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1answer
45 views

What minerals are in this rock? [closed]

Can anyone venture a guess as to what minerals are in this rock? I’ve had it for years and have never been able to identify it. I believe I got it somewhere in Northern California but it was from a ...
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0answers
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Is this Black Serpentine?

I found this rock at a lake edge in Co. Sligo Ireland,its shiny black,leaves a black streak, weighs 320 grams displaces 125ml of water which gives it a density of 2.56 https://www.youtube.com/watch?v=...
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The differences on the atmospheric transportation for various trace metal in atmosphere

I have known that the atmospheric lifetimes of chemical species were highly dependent on their physicochemical properties. For example, $SO_2$ might exist for 5-8 days, while $NO_2$ could only exist ...