Michael Walsby
  • Member for 2 years, 7 months
  • Last seen more than 1 year ago
Why does the salt in the oceans not sink to the bottom?
38 votes

When dissolved in water, salt breaks up into sodium and chlorine ions, which combine with water molecules so they cannot easily sink. However, there is a tendency for streams of fresh water to float ...

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How are hillsides farmed?
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13 votes

Terrace farming is widespread in the Orient but it is backbreakingly labour intensive. In UK we don't do it, partly because we don't grow our own rice. Depending on how steep the hill is, we either ...

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How does a subduction zone form mountains?
5 votes

When the subducted oceanic plate slides beneath the continental crust, it causes crustal thickening and sometimes crustal folding. In addition to this, rising plumes of magma are created when the ...

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The halocline and sonar
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5 votes

Because of the limitations of wartime sonar, U-boats could sometimes pass undetected into the Mediterranean through the Straits of Gibraltar, but it was always risky and avoiding detection couldn't be ...

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What was there before the Paleolithic and where really did life start for us humans, not like homo?
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5 votes

Forty years ago, protein electrophoresis and other molecular types of dating were pointing to a date of 4.5 million years BP for the separation of the hominid line from the pongid (great ape) line, ...

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How did forests end up covering pyramids?
4 votes

Most of the Mexican pyramids are less steep than their Egyptian counterparts, and have niches and terraces which their Egyptian counterparts don't. An important difference is the climate, which is ...

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why continents do not subduct
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4 votes

It is continental crust which hs the greater buoyancy, so when it meets another plate of continental crust neither can subduct. Instead, they collide, crumple and fold, making them thicker and higher. ...

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Does the geothermal activity influence the climate in Iceland?
4 votes

You have already hit on the reason Iceland has such a mild climate: the Gulf Stream. Geothermal heat does not measurably affect the Icelandic climate unless you make your measurements very close ...

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Does Antarctica have a lot of aquifers?
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4 votes

Yes. So far as aquifers are concerned, Antarctica is just like any other continent. The Ice is 4 kilometres thick in places, but at the bottom there is water. If there is any place where water is not ...

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Is there a general equation to know how big of an area is affected by an earthquake?
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4 votes

No, there isn't, because the area affected depends on so many factors, some of them unknowable. Magnitude, cause, depth, geology (which may be very variable in different parts of the area) etc. ...

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How do we know the rate of decay for radiometric dating is constant?
4 votes

First of all, you shouldn't take creationists seriously; like flat earthists, their views are totally out of touch with reality. Rates of radioactive decay have been tested many times in the ...

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How to make Martian soil
3 votes

Just as there are many different rocks and soils on Earth, so there are many different rocks and soils on Mars. To reproduce a Martian soil, you need to bear two things in mind. Firstly it should have ...

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Centripetal Force Perfect Ball and Water
3 votes

If the Earth were a perfect ball, which it is not, and had a perfectly smooth and even surface with no basins or irregularities, water would tend to move toward the equator, where it would form a ...

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How can the Simpson Desert be the largest sand dune desert in the world?
3 votes

The controversy over the largest sand desert is like the controversy over the longest river. Both Nile and Amazon are often quoted, and I have seen claims for the Mississippi. The Nile is favourite. ...

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Are we experiencing lower level of gravity now compared to past?
3 votes

The whole mass of the Earth, mantle, crust, atmosphere and sea, contributes to the Earth's gravitational field, not just the core. Unless you want to split hairs, the Earth's gravity is the same now ...

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Could an earthquake on flat land still kill someone without any buildings/boulders or such near by?
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3 votes

Yes, a man in the open sitting on grass could be killed by a magnitude 8 or 9 earthquake, but in the circumstances you describe it would be very unlikely. Not all large earthquakes produce huge rifts ...

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Why does foliage coloration vary on north/south sides of ridge (Northeast USA)?
3 votes

Your photo doesn't show the strip of autumn-coloured trees very well; without your description I would have taken it for a strip of bare earth. All sorts of things could account for the autumn shades, ...

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How much did the worst volcanic eruption in human history affect global temperature?
3 votes

The largest volcanic eruption in human history was the Toba eruption on Sumatra about 75,000 years ago. There is still a huge lake, Lake Toba, in the crater. It dwarfed Thera, Krakatoa and Tambora. ...

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Tornados from landspouts or gustnados
3 votes

Although there is a superficial resemblance between tornados and dust devils, they are very different. There is no connection between the two. I have seen lots of dust devils in reality, but tornados ...

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Do earthquakes produce folds on rocks?
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3 votes

No, earthquakes are sudden, often very energetic events which produce faults and discontinuities. There is a sharp break in the strata when subjected to a powerful earthquake. The folding of strata is ...

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Possible and probable source of Curiosity Rover's $\small\sf{CH_4}$ detection on Mars
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3 votes

The possible source of methane is biological, and that is what everyone is hoping for, but the more likely source is geological, produced by chemical reactions between rock and water deep underground ...

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Why does chlorophyll only come in green?
3 votes

To ask why chlorophyll is green is a bit like asking why haemoglobin is red. That is just the colour of them, in the case of haemoglobin due to the iron content and in the case of chlorophyll probably ...

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Why isn't the side of the earth facing the sun completely illuminated by sunlight from the north to the south pole every day of the year?
2 votes

You give the answer in your question when you say the earth is tilted (on its axis). Because of this tilt, in winter the northern hemisphere is tilted away from the sun, so for a short while the north ...

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What are the differences between down-looking and side looking radar?
2 votes

Both down-looking and side looking radar look down. Down-looking radar illuminates terrain forward and below the aircraft to detect targets on or near the ground. Stationary targets would be lost ...

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Why did the Australian bushfires cause pitch darkness during the daytime?
2 votes

It was a combination of thick smoke and pyrocumulus clouds. Possibly there might have been other types of cloud as well, Ash rising on the updraught may also have been a factor. I am informed that ...

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CO₂ level is high enough that it reduces cognitive ability. Isn't that a reason to worry?
2 votes

You are being alarmist. $\small\mathsf{CO_2}$ levels vary considerably from place to place, but as you know, the average level is just over 400 ppm. You have a higher level than that in your own lungs ...

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Rain Water vs Sprinkler Irrigation
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2 votes

I think what you mean by thermo-electric nitrogen fixation is the nitric oxides created by lightning discharges. This is absorbed by the raindrops as they form and as they fall to earth, and helps to ...

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How does salting roads help prevent ice?
2 votes

The kind of salt used to keep roads ice-free is rock salt. Rock salt is an evaporite, which was once a salt lake like the one near Salt Lake City in Utah called Bonneville Salt Flats. In the course of ...

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Why are there no mountains higher than ~10 km?
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2 votes

The reason mountains are higher on Mars than on Earth is the lower gravity on Mars, which is only one third of Earth gravity. Mountains are very heavy things, and on Earth the forces that build them ...

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Result of floating-iron-balls in the mid-pacific?
2 votes

I take it that your iron balls are hollow and made of rust resistant steel. It would be a fiendishly expensive project, but I doubt it would have the result you suggest. The iron balls would have to ...

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