49
votes
Accepted
Is there sand in Antarctica?
Yes. In fact, there are sand-dunes in Antarctica [1:15].
18
votes
How much does sea level rise due to sediment deposition?
In a 1983 Journal of Geology paper by Milliman and Meade, "World-Wide Delivery of River Sediment to the Oceans" (link) it is estimated that the world's rivers carry about $13.5\times 10^9$ tonnes of ...
- 1,374
15
votes
Are fossil fuels really formed from fossils?
Let's look at this. A very large number of points for one question.
First, the solar system. We do not see any hydrocarbons in the inner solar system (Mercury to Mars). This is because in this region ...
- 1,082
14
votes
Is there sand in Antarctica?
This LiveScience article suggests the areas aren't major:
The scant areas that are free of snow and ice make up less than 0.4
percent of the continental land mass. In places there, the wind has
built ...
- 8,713
10
votes
Accepted
Large scale structures in the Sahara – what are they?
These features are created by the wind.You will note that the upper left portion has a small dark spot. This is known as Waw al-Namus, or the "Oasis of Mosquitoes." It has a path of material in the ...
9
votes
Accepted
What is the earliest sedimentation we know of?
The oldest known metasedimentary rocks are about 3.8 billion years old, formed in the Eoarchaean era.
'Metasedimentary' just means they have been metamorphosed, so they started out as sediments. They ...
- 11k
8
votes
Accepted
What do you call boulders of non sedimentary rock that were lithified into sandstone?
The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial ...
- 518
8
votes
Accepted
No sedimentation without water?
Not all sediments are deposited in water, but water is important in the formation of most sedimentary rocks.
If we're just thinking about the deposition of the sediment, then we don't necessarily ...
- 11k
7
votes
Accepted
What factors bring sand into or out of the beach?
The amount of sand on the beach at any one time is a dynamic quasi-equilibrium between a whole raft of processes. These include wave power, frequency and direction, seabed angle, longshore drift, rips ...
- 14.2k
7
votes
Are all natural diamonds made of organic carbon material?
Diamond isn't made of organic C at all. Organic matter would rather become oil, gas, coal or dissolve entirely.
C itself isn't very common in earth's mantle, but subducted eclogites and peridotites ...
- 467
7
votes
How are natural specimens, such as ‘Moqui Marbles’, distinguished from man-made artifacts?
Like Michael, I find your question a little unclear, but the crux of it seems to be this:
... does science have to conclude [that a specimen is] just a rock because the composition is entirely from ...
- 5,431
7
votes
Do you have any informations about fossil-rich cherts from Scandinavia?
What you are looking for is information about the "Oslofeltet" (Oslo-field) in Norway (dated to be from the Ordovicium period, 443 - 488 million years old). This is a concentrated field of of fossils. ...
- 1,868
7
votes
Are we observing sedimentary rock formation today?
The transformation of sand into sandstone per se cannot be directly witnessed, as it's happening deep in the earth. However, there are types of cementation that happen quickly and in plain view:
A ...
- 3,548
6
votes
How are natural specimens, such as ‘Moqui Marbles’, distinguished from man-made artifacts?
It's not completely clear what you're trying to ask here, but I'll have a go at it anyway.
If earth only had them would science say there are ancient artifacts from a past civilization?
The only ...
- 23.1k
6
votes
Why is coal classified as a sedimentary rock?
I'm not sure why you are including shale in your question, unless you are referring to carbonaceous shale, which in not coal, but shale with carbon throughout the matrix of the shale.
Shale is an ...
- 24.6k
6
votes
What caused this waterfall to have rounded formations?
Looks like alkali earths ( Ca, Ba , etc.) carbonates deposited from a supersaturated hot spring. As the water emerges from the spring, carbon dioxide leaves the water and the water cools, it ...
- 1,033
6
votes
What makes sand dunes shaped asymmetrically?
Saltation cannot proceed up a steeper slope under the wind conditions that prevail in the particular dune's formation. Dunes are basically traffic pile ups for wind driven sand grains, the slip face ...
- 4,260
5
votes
How to model bed load transport in channels of non-rectangular cross sections
There are several approaches to answer this question. One is simple, but not that accurate. This approach would be to to discretize points along the perimeter and calculate a per point boundary shear ...
- 111
5
votes
How have global sedimentation rates changed over the last billion years?
Big question.
There is not enough data resolution at the moment, neither spatially nor temporally. There are geological periods thought to have undergone higher erosion rates based on the abundance ...
- 1,723
5
votes
Are all natural diamonds made of organic carbon material?
Not so fast, we can't say that 'no diamond is made of organic carbon'. There are two types of diamond, based upon the relative abundance of $^{12}C$ and $^{13}C$ isotopes. The 'lighter' carbon (...
- 14.2k
5
votes
What factors bring sand into or out of the beach?
There's a huge literature on this problem, and depending on who you ask you will get different answers. I'll come at it from the geomorphology perspective.
The most uninformative explanation is that ...
- 432
5
votes
Accepted
Do any rivers deposit sediment in their deltas fast enough to counteract sea level rise?
This is a hugely complex subject for which a categorical answer requires detailed river basin modelling and process calibration. The short answer is that in the short term many rivers deposit sediment ...
- 14.2k
5
votes
Accepted
A sedimentary rock with only minerals
This is a really bad question, because all three can lack fossils, or all three can have fossils. The definition of "minerals" is also a bit unclear, because fossils are also made out of minerals. I'...
- 23.1k
5
votes
Are fossil fuels really formed from fossils?
The definition of a fossil is "evidence of past life preserved by geologic processes".
By this definition a coal bed is itself a fossil since it is the preserved organic matter from an ancient ...
- 822
5
votes
Accepted
In an Earth-like planet with no history of carbon-based life forms, would there be limestone?
I'd have to say, yes. Once life evolved in the world's oceans, the vast majority of limestone formation has been through the organic process. However, before life did evolve, limestone formed through ...
- 2,177
4
votes
What is the maximum grain size of a sediment that can be point counted using a standard thin section?
you might have guessed: There is no such an easy answer as a precise, always valid maximum grain size.
Point counting is an upscaling technique. It works when the sample area you inspect is >= to the ...
- 231
4
votes
Accepted
How this sedimentary rock is made?
The rock you show is a conglomerate - it contains a substantial amount of clasts (your pieces) that are gravel or larger size. The pieces have been cemented together into a new rock - kind of like ...
- 4,429
4
votes
What, exactly, is angle of repose, and where is it in this image?
Geological materials such as sediments are never totally homogeneous. There will always be softer and harder regions within sedimentary deposits.
The fact that erosion channels have been created is ...
- 24.6k
4
votes
Is Radiocarbon dating flawed?
I will preface this by saying that I am not particularly familiar with radiocarbon dating techniques, and therefore the minutiae are somewhat lost on me. However, as someone who works with several ...
- 415
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