Questions tagged [sedimentology]

Sedimentology encompasses the study of modern sediments such as sand, mud, and clay, and the processes that result in their deposition.

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120 views

Can a braided fluvial create thick relatively continuous siltstone beds?

I am attempting to interpret an outcrop I went to. I suggested it was created by a braided fluvial. The one thing I cannot explain are prominent alternating siltstone beds with the sandstone beds. ...
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Have we looked for human-like signals in the geological record?

This is somewhat of a follow up to some interesting discussion here about using synthetic radioisotopes to define the start of the anthropocene. It is also sort of related to a question asked here, ...
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Have meteorites been found in the oldest sedimentary rocks?

Dropstones sometimes occur in sedimentary rocks. These are foreign rocks and boulders that happened to "drop" into a sediment and were fossilised when the sediment was lithified. (source: ...
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Can we separate a sandy, clayey & salt layer on basis of their rheological properties?

Since, given enough compaction, salt is able to behave like a fluid & buoyant too if it's overlain by a higher density rock (it could be fine grained clay or a sandy sequence). But in another case,...
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What kind of soil is being worked in this video? [closed]

I have recently stumbled across this video on Youtube, where quite a magnificient building is carved into the soil with simple tools like a shovel and hoe. The location is somewhere in South America, ...
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Mass budget of coastal erosion and ocean deposion

This question made me wonder: how much mass (or volume) of material is eroded by the sea each year? Of this mass, how much is deposited in the oceans? (As Michael pointed out in his answer, part of ...
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Why is coal classified as a sedimentary rock?

Something just clicked in my head today. Rocks, by the definition I was taught, are composed of minerals which in turn are by definition not organic, so they are or were not alive. However. Coal, ...
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How are chenier ridges and strand plains formed at wave dominated coastlines?

In the attached image, we can see chenier ridges and strand plains. How are they formed and what is the involvement of rip and longshore currents in their formation?
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When sediments are deposited, do they sink into the earth?

I was listening to a geology podcast describing how sedimentary rock forms and later turns into metamorphic rock. As a river lays down sediment, the lower layers can eventually be several kilometers ...
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what kind of rock or mineral is in my pic [closed]

I'm trying to identify this sediment. Any ideas of what its named or how its formed?
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Sedimentology (Particle size distribution parameters)

The Inclusive graphic standard deviation (sorting) value of this claystone sample is negative (-1.29). Is this right to be considered as very well sorting ? However, the bivariate plots of ...
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Is there any significance of lacustrine gastropoda fossils regarding paleoenviroment interpretation?

How to interpret lots of gastropoda fossils seen in lacustrine marls? Do they indicate any paleoenvironment conditions? Depth, temperature, chemistry, ph?
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Sandstone Layer Question

I have been exploring the sandstone of southern Utah for many years and I have a question about the area around Sidestep Canyon (near Wahweap, near Page, AZ). There are many amazing hoodoos there and ...
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How much does the weight of urban structures (buildings) affect the compaction (permeability, porosity, density) of alluvial sediments below a city?

I live in Van, Turkey. Van City is situated on an alluvial plain beside Lake Van. General geological structure of the area can be seen on pages 43-44 in this conference book. One of the images is ...
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No sedimentation without water?

I just found a video on sedimentary rock formation, and to my surprise, it stated that this only could occur in water! I always thought that any layer of matter, if buried deep underneath more matter, ...
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How do I plot Troels-Smith lithological symbols in R?

I'm trying to plot lithological data using the Troels-Smith scheme. I have tried psimpoll but as I only have lithological data I cannot create a main input file which is required. I also do not have ...
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How are natural specimens, such as ‘Moqui Marbles’, distinguished from man-made artifacts?

If a particular type of rock specimen is found throughout Earth and is made entirely of natural minerals, but the individual specimens differ minutely from another in size and shape and look to be ...
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How this sedimentary rock is made?

Apologies in advance for a beginners question. Different rock types make me curious and recently went to an area where interesting sedimentary rock is all over. As the area is on the coast, sea has ...
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Geological feature - what is it?

Hello, We were walking in Bundoran in Donegal County, Ireland today and we encountered the geological feature shown in the picture (from above from cliffs and from very close up at beach level). We ...
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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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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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How much does sea level rise due to sediment deposition?

There has been a lot of noise in the news in the last few days because Congressman Mo Brooks from Alabama claimed that erosion played a role in rising sea levels. Quoting from Science magazine: ...
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Waves on sandy beach separating differently-sized rocks?

I recently went to a beach, and I noticed that the sand seemed to have a few distinct regions. I'm wondering what would cause this, and how it works. One region is the part of the beach which is ...
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What are the differences in terms of appearance between sandstone and limestone?

On the field, I find it very difficult to differentiate the two types of rocks just by looking at them.I know that you should do some analysis of the sample before any conclusions. But, for example in ...
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A few questions about the morphology and sediment dynamics of Wissant Bay (France)

Could someone please explain what exactly is shown on the following image? I have a few questions such as: How did the 'Banc à la Ligne' come about? (I know it has something to do with the fact that ...
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What is the difference between Saprolite and Regolith?

Saprolite and Regolith both imply loose material, is one a subset of the other how can I differentiate them ?
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What are these basal rip up clasts in North Dakota?

Ther's an graph that appears that the KT asteroid turned the rocks into rubble 3000 km away, else there was a rain of big rocks from the sky. What are the rip up clasts and what is the way they were ...
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How do you interpret Oxygen Isotope changes?

In a paper I am reading, the authors note "large (5-7%) negative shifts in the oxygen isotopic composition of geologic proxy materials" (Davis 2008, pg. 102) in several regional basins. This is then ...
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Is there sand in Antarctica?

There's a song "Blizzard's Never Seen the Desert's Sand". Given Antarctica is a desert, someone questioned the title's validity. BUT is there sand in Antarctica? I'd imagine yes as it's a pretty ...
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Does the existence of limestone nodules in a clay soil horizon indicate a limestone bedrock?

A profile (clay soil) was excavated to a depth of 100 cm in the north of Tunisia. We have found limestone nodules, colluvium and alluvium. What I would like to know is the nature of the bedrock of ...
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Are all natural diamonds made of organic carbon material?

I've read that diamonds are created at a depth of about 180 km. By volcanic activity it comes above. But did plants and trees of 300 million years ago sink so deep? Or is it possible that inorganic ...
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How much climate history can be reconstructed using marine sediment cores?

Today I learnt in college that marine sediments can be used to reconstruct the climate up to 500 million years back. I find that number very strange because in another class we learnt that the ocean ...
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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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What is the difference between eluvium and alluvium?

I was reading about kimberlite on Wikipedia and it mentioned eluvium. I've heard of alluvium, alluvial fans, alluvial deposits, etc. However, when I looked up eluvium, it sounded exactly like alluvium....
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In an Earth-like planet with no history of carbon-based life forms, would there be limestone?

The extent of my understanding of limestone is about what Wikipedia says at the very top of the page: Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such ...
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Where can I find papers on the geology of the Wastach Range in Utah

I am looking for papers on the stratigraphy, geochronology and/or compositional make up of the Wastach Range and its formations. I prefer a broad overview paper and I can't seem to find one. Any help ...
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How are the Scala dei Turchi staircases formed?

The Scala dei Turchi i (Italian: "Stair of the Turks") is a rocky cliff on the coast of Realmonte in Italy: https://en.wikipedia.org/wiki/Scala_dei_Turchi#/media/File:Scala_dei_Turchi_panorama.jpg ...
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How are sand blocks formed?

My son asked me at the beach how are "sand stones" formed. These are the solid (but fragile) sand conglomerates which you can hold in your hand and which crumble to sand once pressed. I tried some ...
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Presence of cross stratified conglomerates in fan deltas

Why are cross stratified conglomerates found in deposits of fan deltas? I know that fan deltas are alluvial fans that deposit directly into the sea, hence they are poorly sorted.But could not ...
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How to model bed load transport in channels of non-rectangular cross sections

All the formulas presented in the relevant technical literature refer to channels of rectangular cross section — the formulas assume a constant depth of flow right across the channel section. I need ...
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What are the differences between alluvial, eluvial and colluvial deposits? [duplicate]

There's always confusion and disagreement when these terms are mentioned. Need to be sure of their exact meanings.
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457 views

Inorganic Limestone and Inorganic Gypsum

I read that limestone is made from the compaction of marine animals' bones. But, I am unable to find out why limestone could not have been produced from calcium occurring naturally (5th most abundant ...
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Geology: facies v. formations

Can someone please explain the difference between sedimentary facies and formations?
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Are fossil fuels really formed from fossils?

Hydrocarbons have been found in great abundance elsewhere in the solar system where there is unlikely to be evidence for life past or present. No fossils involved. Petroleum and natural gas wells ...
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Formation of petrified trees

In my book, I came across this question: Give reason why formation of petrified tress is considered as a degradation and a sedimentation action of the underground water. My book explains that ...
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Deposition in epioceanic areas

I found allochthonous (I don´t know the 2 locations) fined grained carbonate sediment in Ammonitico Rosso, which is possibly mudstone in the South Iberian Peninsule, specifically in Carcabuey (Córdoba)...
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The grains of the parabolic dunes

My text book says that parabolic dunes consist of consolidated limestone grains, but I wondered if they have sand grains too, so I googled this issue and found that they consist of sands, but I am ...
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A sedimentary rock with only minerals

In my text book I came across this multiple-choice question A sedimentary rock consists of only minerals and lacks fossils, it could be classified as: i) a clastic sedimentary rock ii) a chemical ...
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What is limestone made of?

I know that it is calcium carbonate (CaCO3). I also know that these are the dead bodies of microorganisms. My question is, where do they procure the building material? The limestone seems to cover ...
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How can we estimate the amount of sediment that traveled downstream during the California flood?

It's amazing how much water traveled down the slopes of California during the first two months of rain/flooding of 2017. Since the amount of water was far greater than anything in recent history, ...