# Tag Info

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### Is there sand in Antarctica?

Yes. In fact, there are sand-dunes in Antarctica [1:15].
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### Why is Mauna Kea taller than the maximum height possible on Earth?

Since over half of the height of Mauna Kea is under water, you need to consider the buoyancy effect. Instead of a density of $3 \times 10^3\ \mathrm{kg/m^3}$, the underwater portion has a net density ...
• 1,158
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### What are these lake-like blue patches in the desert, visible in satellite image?

The 'bluish' areas are exposed gypsum and gravel across which the sand dunes are moving. The colour is likely an artifact of the 'natural' colour palette used when processing the SPOT image. To ...
• 186

### How and why do these tree-like river structures form?

The river isn't splitting. The picture shows a number of dendritic drainage channels flowing into a larger river/stream. They are the most common form of topographical draining system. They develop in ...
• 21.8k
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### What is this weird looking structure in Ethiopian desert?

Zoom in for the clues. The lines are not radiating out from the village, but from the cattle kraals. These kraals are irregular enclosures built of acacia thorn, agave and other thorny bushes. The ...
• 14.1k
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### How did the Ural mountains form?

The Ural mountains are one of the oldest mountain ranges on Earth. They started forming about 300 Ma ago by the subduction of the oceanic crust once attached to the Kazakhstania plate under the ...
• 17.1k
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### How do long rivers exist?

Well, I can only agree that it is indeed amazing and it doesn't get less amazing when some geology, hydrology and geomorphology is added to the the amazement. All precipitation that falls on land ...
• 5,896
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### Why are deserts mostly located on the western side of continents?

Some of the driest deserts on Earth occur in the western side of continents and they are called Coastal Deserts. Examples of such deserts are the Atacama desert (Chile, the driest desert on Earth), ...
• 14.7k

### Could a massive flood have formed the Grand Canyon?

tl;dr: no. Long answer: First of all, like mentioned by others in the comments, you would need some physical mechanism to take a whole lot of water, evaporate it, and drop it at once at a place ...
• 22.2k
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### How are giant sinkholes filled up?

How Japan Filled That Ginormous Sinkhole In Just One Week: The Fukuoka sinkhole measuring 8,700 square feet (808 square meter), 65 foot (20 m) deep: they poured a mixture of soil, water, and cement ...
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### 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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### How do long rivers exist?

I will attempt at rephrasing your interesting question after these considerations: At the continental scale, flowing water has no significant inertia, so water flows following the maximum slope. A ...
• 1,673
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### Strange craters in Afghanistan

These are qanats, a type of antique drainage system common in arid climate regions of the Middle East, particularly in Iran (as mentioned by @Spencer @Winwaed). Some of those are still in use for ...
• 2,633
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### Why does this shoreline change this way?

Short version; the beach moves because the waves change. Long version; Beaches, and in fact entire bays, conform in shape and alignment to the prevailing wave patterns in the area. The exact magnitude ...
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### Why is Mauna Kea taller than the maximum height possible on Earth?

Your calculation of maximum height has a precision of one significant figure, 10000 meters. That is consistent with the height of Mauna Kea to the same precision of one significant figure. The ...
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### The river or the hills; which came first?

This is a kind of chicken or egg question, since there was never really a point at which there was no river flowing, or no hills to flow around. My question is whether the hills preexisted the ...
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### Origin of Andaman and Nicobar islands

The Andaman and Nicobar Islands are neither orogenic or volcanic in origin. They are in fact an accretionary wedge, i.e., an accretion of sediments and oceanic crust "scraped" from the ...
• 5,793
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### How are minor tributaries of a river determined?

This is a question of topology. There are three major attempts to order streams from small to larger. The first was established by Horton (1941) who established the concept of drainage composition. ...
• 4,536
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### What is the purpose of this large structure on a Japanese hillside?

The structure looks similar to this photograph of a "Japanese land retention system" mentioned in passing towards the bottom of this webpage. From the linked page: Land retention systems in Japan, ...
• 5,380
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### Esker vs. Kame vs. Drumlin - what's the difference?

Eskers are glaciofluvial deposits from sediment carrying subglacial tunnels. As the water emerges from a tunnel at the bed of an ice sheet or glacier it will slow down. Since the sediment movement ...
• 4,536
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### How did sand dunes appear in the midst of a fertile region?

It appears the sands at Talakad are the result of a ecological disaster that occurred in the 17th Century. At the time, a dam was constructed north of Talakad on Kaveri River which caused the river to ...
• 21.8k
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### Identifying a desert landform

Star dunes, caused by the prevailing winds coming from multiple directions. Take a look at these different dune types.
• 6,558
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### Similarities and differences between lava flows and fluvial geomorphology (rivers)

The similarities pretty much end at the fact that both water and lava flow downhill seeking the lowest possible level. As even the most fluid lavas flow somewhat slower than water because of their ...
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### Geomorphology of Mountains With Wind only Erosion

You do have an earth analogue for this. The Namib Desert in Namibia has been a desert for the past 2 million years with very little precipitation. Also the Atacama Desert is hyperarid since more than ...
• 472
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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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### Could a massive flood have formed the Grand Canyon?

In addition to all of the above there are meanders inn the Grand Canyon which are hydraulic outcomes of 'minimum energy flow configurations'. This constrains the discharge rates that are possible - to ...
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### A circle shape in Madagascar

It is an extinct volcanic crater. The location is not listed as one of the active volcanoes in Madagascar. Simplified geologic map of Madagascar (reference) shows the crater to be mapped as basaltic /...

### Why are deserts mostly located on the western side of continents?

Because of the Coriolis Effect, the prevailing winds on the earth between about the Tropic of Capricorn and the Tropic of Cancer go from the East to the West (knows as the Trade Winds). To get to the ...
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