# Tag Info

45

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

22

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 of $2 \times 10^3\ \mathrm{kg/m^3}$. That will significantly increase the potential height of such a mountain. Add in all the other uncertainties (is Mauna Kea ...

18

Starting from the bottom of your question I would not compare planets with plate tectonics with planets that don't have this process. During rifting of a tectonic plate a triple junction will be the most favourable way of faulting the crust. After that two arms of the rift are favoured and the third one becomes a failed rift (aulacogen). Because of this ...

17

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 gently sloping topography and they ... develops in regions underlain by homogeneous material. That is, the subsurface geology has a similar resistance to ...

16

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 must flow back to the oceans somehow, and unless it evaporates it will flow in rivers or as groundwater towards a lower hydrostatic level. Water can not flow ...

16

A clue is in the full name of the hill: 'Butte Montmartre'. A butte is an erosional feature in which a block of resistant rock overlies a less resistant layer. Erosion of the soft layer below causes the more resistant rock to erode as well by undercutting. This can lead to an isolated hill in a relatively flat surrounding. The Montmartre hill itself ...

16

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 ancient Laurussia continent. A subduction process that finished about 240 Ma ago. The tectonic plates are far from fixed, some of them disappear over time other new ...

15

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 understand just how arbitrary and variable the results of that processing can be, consider the following image captured at a fairly high zoom level in one of your '...

15

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), the Baja California desert (USA/Mexico), the Namibia desert (southwestern Africa), and the Atlantic coastal desert of Morocco/western Sahara/Mauritania. In mid-...

14

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 where the Grand Canyon is now. This is not something that's going to happen because of physics. If there was some extraordinary event which could have caused this, ...

14

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 into the hole—they use more than 7,100 cubic meters of the stuff in all. YouTube timelapse. How To Fix a Giant Sinkhole about the two in Guatemala: The first ...

12

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 river is just a path along the continent that follows the maximum local slope at any of the places it passes through. What amazes you (let me interpret) is that ...

12

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 storage because of lower underground temperature or to access the underground water. In the picture posted by OP, it further make sense since the underground ...

11

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 difference, 210 meters, doesn't matter. Your question doesn't really make sense the way you have stated it. You need to propose a model, and do a calculation, ...

11

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 course of the river or did the river in some way cause the hills to "appear". Most of the area which you describe along the Mississippi is formed of sand, gravel ...

11

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 sand dunes. This article by Burton-Johnson et al., 2016 on automated satellite analysis methods, summarized in this DailyMail article, indicates refined ...

10

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. To establish the relative importance of streams in a network Horton suggested to investigate each junction and to set the stream that entered the junction at ...

10

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, for example, are often designed as heavy waffle grids which are molded to the topography and cover it to a uniform structural depth. This seems to correspond ...

9

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 be diverted. This exposed a sand deposit in the river which was subsequently moved to Talakad by monsoonal winds. The following quote is from this source AB ...

9

Star dunes, caused by the prevailing winds coming from multiple directions. Take a look at these different dune types.

9

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 depends on water velocity the sediment will be deposited. The results is a highly localised deposition. When glaciers retreat the point of emergence for the water ...

8

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 25 million years. Mars is probably a planet that has below freezing temperatures for million of years, with only wind as an erosional process (apart of a few ...

8

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 part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by ...

8

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 within the normal range of hydrologic discharges. Furthermore there are several places in the Grand Canyon where there is clear evidence of the river having ...

8

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 / Gabbro lava,

7

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 west coast of a continent within those latitudes, an air mass blowing from above an ocean must cross the entire continent. Along the way, the air mass causes ...

7

David Hammen has already answered with the correct term in his comment. Karsts are formed as water dissolve rocks, typically carbonates (as limestone or dolomite) or evaporites. Karst landscapes can originate from karst caves, formed by groundwater flowing through the rocks. When the caves eventually collapse (see image here) a rugged landscape is left ...

7

Near the Lake of the Woods, the island swirl or vortex is due to structures in bedrock beneath the lake. The rocks in this area are old and have been folded by tectonic action. The area has either been folded into a dome or a basin, exposing different layers of bedrock. Glacial activity afterwards has 'flattened'the area, and differential erosion within the ...

7

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 subducting Indian plate. See for instance the description in the first chapter of the aptly titled The Andaman–Nicobar Accretionary Ridge: The islands are an exposed segment ...

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