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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19 views

Rock put through strainer? What kind of rock is this? [on hold]

My son loves picking rocks. He found it on our driveway which is crushed gravel. Is this a rock? If so what kind of rock is it? You can clearly feel the bumps. It's as if rock was forced through ...
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If two adjacent tectonic plates are moving in the same direction, is there significant interaction at the boundary?

If two adjacent tectonic plates are moving in the same direction, is there significant interaction at the boundary? Is it just a convergent boundary if one moves faster and "catches up" with the other?...
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Can a rock have a Vp of less than 1000 m/s and need blasting to excavate?

I have run a 60 m refraction seismic line on a mountain summit. The environment was noisy (wind would be the principal agent) and quite difficult to pick first arrivals. It resulted in 800 m/s. A ...
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How did this hole / hollow form within this rock?

Can you assist me in understanding how this hollow was formed in this rock. I am told that it has to do with cementation but I believe that geological process produces rounded canonball ( sometimes ) ...
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Could someone tell me what this stone might be [closed]

It is 9 1/2 inches by 3 1/2 inches and weighs about 5 lbs. it was at this house in Florida when we bought it. It has a white 1/4 inch crust and the interior color looks somewhat topaz.
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What Makes Round Holes In Superior Agates? [closed]

I found this rock in Western Wisconsin. Pretty sure it's a Lake Superior Agate? Wondering what would make the white eye that has red in its center? Would this rock be a good one to have someone cut ...
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where are the poles of rotation of the tectonic plates located?

Euler's "fixed point" theorem ... can be stated as: The most general displacement of a rigid body over the surface of a sphere can be regarded as a rotation about a suitable axis which passes ...
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“Obicular” structures in basalts

I found spherical or globular structures, structures in basalts of a greenstone belt which underwent alteration and deformation. However, in thin section, these structures have undeformed pyroxene and ...
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Utah rock pattern identification - looks like small craters

This formation was found in the Capital Reef area of Southern Utah (38.2970546, -111.2979319). There wasn't just one, but several of these small crater formations all over the area. All of them had ...
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1answer
454 views

Fossil or Beef Limestone?

I found the below sample on Monmouth Beach near Lyme Regis and I am unsure if it is a fossil or simply beef limestone. The beef limestone is from fibrous calcite layers within a shale (known as shales ...
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68 views

Can living where magnets are abundant provide a mini-magnetoshere?

Are there a mini-magnetosphere within the magnetosphere similar to mini-magnetosphere found on the Moon? Is there a map of these areas that would resemble the white swirls in the picture below? The ...
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What are these features in the Tombouctou Region?

I’ve recently been very interested in globe-trotting via Google Earth. At first I was using it to plan out hikes to possible mineral deposits locally, or potential fossils/ archeology sites. However I ...
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Is there any mineral identification techniques that works for all minerals?

Are there any mineral identification techniques that work for all minerals(non-metallic/metallic), so that an electronic device could be made to distinguish between all minerals?
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How can I tell the difference between granite and syenite?

(I'm not a geologist, just helping my kids collect rocks).
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Marks on boulders of volcanic origin

I am working in a catchment in the southern Ecuadorian Andes, about 3700 m.a.sl. Rock outcrops at the upper part of the catchment, as massive blocks varying their size from one meter up to five meters,...
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380 views

Any idea what are these circular rock marks?

During a family trip in the Israeli National Trail in the Pora Stream part (31.496871, 34.770928), I noticed these circular rock marks. Any idea what are they?
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Muscovite with pleochroic halos?

Is it possible to find pleochroic halos in muscovite ? I would have said that it must be biotite (also, in PPL it is brown!), but then.. why does it have interference colors so similar to muscovite ? ...
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how can a asterisk/star like crack occur on a rock?

how can a asterisk/star like crack occur on a hard pyroclastic rock? Could it caused by a meteroite or by some other mechanism? You may see the shape of the rock on attached photo.
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What is this island or reef 600 km east of Marianas Islands?

This map shows an island a bit east of the Marianas. I took a screenshot of the relavent part. I hunted around for it in Google Earth with no luck, but I did find a promising candidate here: I could ...
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Where are these volcanos as seen in this space tweet?

In his recent tweet from the International Space Station as it's current Mission 56 Commander, NASA astronaut Andrew J. Feustel says: This is #Indonesia as viewed from the @Space_Station. With the ...
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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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174 views

Why would CaO be more finely spread than K2O in Granodiorite?

I recently interpreted some XRF data on samples of a granodiorite which were classified under three different types of physical characteristics: very little, mild and significant levels of weathering. ...
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161 views

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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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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What do you call boulders of non sedimentary rock that were lithified into sandstone?

I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes ...
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The geology of local landscapes and small scale features

I'm learning geology to understand the processes behind the formation of my local landscape. I understand the processes behind big features, such as mountains. But I'm struggling to understand the ...
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135 views

What caused this waterfall to have rounded formations?

This is at Bua Tong Waterfalls in Chiang Mai, Thailand. Tried to find scientific information about this waterfall, but google turns up only travellers' vague guesses, suggesting calcium carbonate ...
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Fossils in this rock from Montana? [closed]

I found this in SE montana. It feels quite dense and is about 1.5". The lighter colored divets cover the entire thing and some have holes going deeper into the stone. I was told it could possibly be ...
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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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Hypothetically, what would happen to the earth if a large hole was drilled through the center?

This may be a slightly unusual question. I know it wouldn't be possible, but what would the short and long term effects be, if a large (say, 1 mile diameter) round hole appeared, and went straight ...
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262 views

What is the global distribution of oil filled geodes?

In a general 40 mile radius of Keokuk, Iowa many sedimentary geodes can be found. They are abundant in the Warsaw Formation with the type section at Geode Glenn in Warsaw, Illinois. In one specific ...
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Climate consequences of very large asteroids striking the Deep Ocean

For every asteroid or meteorite that hits dry land, two hit the sea. If a Manicouagan-sized asteroid struck the deep ocean (but not above a trench),how would the H2O vapour, chlorine, iodine bromine ...
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Why is Earth's inner core made of an iron-nickel alloy?

This question has puzzled me for a while. I know that earth's mantle is made of different minerals, metals and rocks etc. and that has always made complete sense to me. But why is the inner core made ...
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Why is the temperature between the earth core and surface not distributed linearly?

So I read somewhere that the inner core temperature of Earth might be as high as 7000 °C. Depending on the composition of the different layers towards the surface, the temperature should decline ...
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How could this pyramidal Mountain have been formed?

How could this pyramidal peak have been formed in Antarctica? Little is known about it as far as I know but what is known is that its miles away from any existing plate boundary and its shape is also ...
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Is there any possible future for high energy geophysics? If so how it is going to revolutionize our knowledge about Earth's interior?

How practice is to map/image the subsurface of the earth using the high energy particles like neutrinos? https://www.geosci-instrum-method-data-syst.net/special_issue2.html
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What is the History of the Brooks Range?

This here is a map of the Brooks Range in northern Alaska: As you can see, it is an inland range shaped in a downward curve. Why is that? What is the history of the uplift of the Brooks Range? How ...
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Rock ID: black rock found in Central Europe [closed]

I'm note sure if it's an anthracite, augite, jet (lignite) or something completely different. I don't know where exactly i found it because it's from my old rock collection. I would appreciate your ...
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How Can We Establish Precisely What Earth's Core is Made Of?

The consensus view is that that the Earths core is composed mainly of iron alloyed with about 10 percent nickel and traces of other heavy metals, but I have seen at least one account which says it is ...
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Rock ID: smooth, black, durable rock from Lake Ontario [closed]

What is this black rock? I found it beneath the waters of Lake Ontario near the shoreline, it is a dark greyish-black with small flecks of mineral deposits on it that are visible in the light. The ...
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Help! Can anyone identify this deep blue rock, quartz, crystal thing from Washington? [closed]

I was like 10 waiting for my dad to get off work. He was a surveyor and brought this blue rock thing with him for me when he got off. He said they were surveying and his friend took a pickax to a rock ...
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Why do crystals, like quartz and diamonds, form in different colors?

Some crystals, like quartz and diamonds, form in a variety of different colors. For example, quartz can be clear, 'foggy', pink, yellow, and even blue. What happens during the crystal's formation to ...
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63 views

What kind of rock is this? (Sedimentary) [closed]

This rock was obtained from a nearby quarrying from our grandparents' house on an island. It has a couple of bronze/mud colored linings on it and a bunch of scattered white areas. Could also see tiny ...
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Can Anybody give me more info on this brecia? [closed]

Hi I have this boulder as part of an arts project in the North East of England. It was taken with Premission from a beach at the mouth of the river Tyne. At first I thought it may have been a glacial ...
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1answer
365 views

Please Help Identify My Rock [closed]

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
121 views

Identification required, rock formation found whilst on holiday in Cephalonia, Greece white object embedded inside? [closed]

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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How and why did the oceans form on Earth but not on other planets?

Earth is the only planet in our solar system that has copious amounts of water on it. Where did this water come from and why is there so much water on Earth compared to every other planet in the ...
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What are these metallic nodules that were found at low tide on the UK south coast? [closed]

Smooth spherical crystalline metal nodules Outside and inside surface does not scratch with a knife blade Inside lustre brassy, radially striated metallic crystals radiating from a lumpy centre at the ...
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611 views

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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I found this stone with metal linings can someone identify it?

I am more curious about the metal on the surface (if it's even metal?) on this stone :) I don't really remember where I found it, probably at this beach of the Baltic Sea, but there is also a chance ...