50 votes
Accepted

Is there sand in Antarctica?

Yes. In fact, there are sand-dunes in Antarctica [1:15].
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18 votes
Accepted

What is responsible for the underwater waterfall illusion of Mauritius Island?

The cause for this phenomenon is sand and silt moving down an underwater cliff as you guessed. The geography that makes this possible is as follows. The island of Mauritius is located on a giant ...
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  • 1,622
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 ...
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  • 1,374
17 votes
Accepted

What are the non-anthropogenic causes of The Netherlands' low elevation?

Forming of coastline During the last ice age, the North Sea was dry. When the ice melted sea levels slowly started to rise again and due to tides and currents a barrier of dunes was formed along what ...
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  • 420
14 votes
Accepted

Is it true that "[sand] grains in the Coconino Sandstone come from the Appalachian Mountains"?

Jeffrey Ralh of Yale and coauthors published Combined single-grain (U-Th)/He and U/Pb dating of detrital zircons from the Navajo Sandstone, Utah, which concludes that Navajo sandstone originated from ...
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  • 5,892
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 ...
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13 votes

What is limestone made of?

The building material comes from minerals dissolved in the ocean, mainly $\mathrm{Ca}^{2+}$, $\mathrm{Mg}^{2+}$, and $\mathrm{HCO}_3^{–}$, but of course there are all sorts of biochemical details. ...
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12 votes

How have global sedimentation rates changed over the last billion years?

Sedimentation rate presently varies many orders of magnitude depending on the place you observe. The rate of sedimentation is also different. Some places have continual sedimentation, others have ...
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  • 3,876
12 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 ...
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10 votes

How does the sand appear on Hawaiian beaches

I think the easy answer comes from the Hawaii Department of Land and Natural Resources: Beaches in Hawaii may be made of 'black sand' derived from the erosion of volcanic rocks, of 'white sand' ...
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10 votes
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What is the oldest sediment?

According to page 86 of Exploring the World Ocean: In December 1989, ODP scientists drilled Hole 801C and recovered Jurassic-age rocks and sediments, about 170–165 million years old, from the ...
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  • 5,892
10 votes

Software for sediment transport modeling

I think the best option for sediment transport modeling is the Community Sediment Transport Modeling System (CSTMS) package that was developed for ROMS. CSTMS was created by a group of sediment ...
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  • 14.7k
10 votes
Accepted

Incised valleys and hydrocarbon potential

Sandstone bodies in incised valleys can be good hydrocarbon reservoirs. Incised valleys form on the coastal plain and/or continental shelf during a fall in relative sea-level by a combination of ...
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  • 10.7k
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 ...
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9 votes
Accepted

Sediment layer chronology

In simple big picture terms, Sediments were deposited first from the bottom upwards (as you understand). Then the area was uplifted and the river eroded from the top down. Most erosion is from the ...
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  • 3,823
9 votes

Identifying sedimentary rocks in hand specimen

When learning to distinguish between siliceous and calcareous samples you should use a handlens. Look for quartz, feldspars or micas. Quartz clasts may be frosted, or you may be able to see ...
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  • 541
9 votes
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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 ...
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8 votes

Determining a rock age using volcanic ash layer

The main interest of tephrochronology (i.e. dating sediments using volcanic ash layer) is specifically its instantaneity (relatively to geological timescale of course). It is precisely used for higher-...
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  • 5,238
8 votes

How have global sedimentation rates changed over the last billion years?

As Spießbürger also mentions in his answer sedimentation rates are local, and highly depend on sediment supply and accommodation room in the sedimentary basin. Global sedimentation rates are then just ...
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  • 2,602
8 votes
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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 ...
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  • 508
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 ...
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7 votes

What is the difference between eluvium and alluvium?

Also keep in mind that eluvium and eluvial have a different meaning in soil science. There, it means leaching of soil matter or chemical substances by water. (Usually, after some downward transport, ...
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7 votes

Software for sediment transport modeling

Large parts of Delft3D - including, I think, the sediment transport module - are available in an open source form. The GUI is not currently open source, but (a) Deltares have been offering licences ...
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7 votes

Can concretions form in non-sedimentary rocks?

Not really. Concretions are features of sedimentary rocks almost by definition. Here's my go at a definition; it essentially presupposes a sedimentary rock: Concretions are spatially discrete zones ...
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7 votes

How does the meridional overturning circulation affect sedimentation rates in the North Atlantic?

Downwelling speeds in the deep water formation areas are likely not significant when compared with the settling speeds of most sediment particles. While deep waters have clearly defined oxygen and ...
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  • 14.7k
7 votes

Formation of limestone without living organisms?

Oolites are limestones that are usually considered as in-organic, although they may have bits of shell/etc in them. These form by the precipitation of calcium carbonate around particles (sand, broken ...
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  • 3,823
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 ...
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