"It depends on what you mean by dirt," says Milan Pavich, a research geologist with the U.S. Geological Survey.
"The oldest sedimentary rocks are about 3.9 billion years old—they're in Greenland—and at one time, they were dirt. That's pretty close to the time the Earth formed."
But those rocks are just proof that dirt existed on the planet way back then. The stuff in your backyard is much fresher. "Most of the dirt you see today is from the past two million years," Pavich says. About two million years ago, the planet underwent two major changes that drove the formation of new dirt. Global cooling and drying enlarged the deserts, and dust storms redistributed that dirt around the globe. Meanwhile, glaciers began extending from near the poles, grinding rocks, soil, plants and anything else into dirt as they moved over the land.
Dirt is still being produced all the time, albeit in much lesser quantities. Beneath the soil's surface, rocks constantly react with rainwater or groundwater and slowly grind together to break down into smaller minerals. So in that respect, dirt really isn't that old. Then again, Pavich notes, a lot of what came out of the big bang was essentially dust, which then condensed to form the stars and, later on, planets. "If you think about it," he says, "dirt and its origin are older than the stars."
This article originally appeared in the January 2010 issue of Popular Science magazine.
Most dirt is actually earth worm dung. This is not a big revelation but I am extremly disturbed at our farmers who depend on the dirt for their crops and kill all the earth worms with their pesticides. Go to an area where there are houses mixed with farmers fields when it rains and look at the worms on the roads. The worms end right at the edge of the farmers fields. Thus no new dirt is made from leaves etc. or aireation (Sorry about the spelling.) of our fields. Something is wrong about this and we need to find a way to keep the worms in the fields before we can't raise crops any more.
Worms help (breakdown of large material to increase surface area and aereation), but it is bacteria that do the job of turning life into soil. Those pesticides are bad for the worms, frogs, and most everything else, but things still rot back into soil, because we could not kill off all the bacteria if we tried.
Oak is right, soil is made irregardless of the presents of worms. I haven't done enough research but I don't know how old soil really is, so I don't believe that it is millions of years old. If that where true we would never have fossils in rock because the rock would never have been made. But still not enough research done on my part to say for sure.
First off, soil is a form of dirt. However, they aren't interchangeable. The term soil is usually used to describe a more organic compound that's broken down plants and animals and fungi. So in that sense, Azorus, you're right because soil is relatively freshly made. Dirt however is more like a broken up form of rock and mineral so it technically can be as old as the stars, given that it could be compressed into rock and then ground back into dirt again.
if the earth were to instantly stop spinning what would happen?
Oak is right, soil is made irregardless of the presents of worms. I haven't done enough research but I don't know how old soil really is, so I don't believe that it is millions of years old.
If that where true we would never have fossils in rock because the rock would never have been made. But still not enough research done on my part to say for sure.
ومع ذلك ، فهي ليست قابلة للتبديل. عادة ما يستخدم المصطلح لوصف التربة مركب أكثر العضوية التي انهارت في النباتات والحيوانات والفطريات.
Curious if the author is accurate, then all rocks should have the same age. Sedimentary rock is just compressed constituents of earlier smaller pieces of rock (dirt), igneous rock is simply earlier rock, melted, spewed to the surface and exposed and metamorphic rock is simply extant substance filled with constituent minerals (dirt). In other words, all forms of dirt and all forms of rock, came from rock that already existed. Thus the rock should display an age equal to the age of the constituents. Rocks are either "created" (ex nihilo - out of nothing) or are "formed" (ab initio - from the beginning). If they are formed, then they should reflect the oldest parts of which they are composed. If they are created, then they would reflect their creation date, but matter would be increasing. Since the laws of physics, in particular, the conservation of matter/energy, states that matter and energy can neither be created nor destroyed, matter cannot be increasing, at least not without a commensurate decrease in energy (which is being converted to matter).
So, if you test the age of a rock and say it was created 3.9 billion years ago, then grind it up (dust storms, plate tectonics, water erosion, whatever) you end up with a pile of dirt 3.9 billion years old. It now washes down a river, into the sea, settles to the bottom and compresses for centuries. However, shouldn't it still show 3.9 billion years old? If so, how do we ever get sedimentary rock that is anything but 3.9 billion years old. You say, fish dung! Where did that come from? Plants, animals, whatever it eats to survive. Where did that come from? On and on and on, until finally you say, it came from the constituent elements that are 3.9 billion years old. Why doesn't everything test 3.9 billion years old. In fact, the earth came from stuff 11 billion years old, why does the earth test at 3.9 billion years old when it was made from stuff that is 11 billion years old? What event changes material in some explainable way where today we are measuring it as part of the 11 billion year old universe, we light a spark and say "poof" today you are brand new and we've erased the 11 billion year old date? What does the erasing, what does the initiating, what stamps the date on the material and what are the chemical and physical changes that occur that cause 3.9 billion year old igneous rock to suddenly turn into ground up, settled, 1 day old sedimentary rock? One day it was dirt on the bottom of the ocean, the next day dirt on the bottom of the ocean, next day, next day, then Poof! it's now sedimentary rock one day old and here'e the thing that changed that we can now measure. On that day, can we say that one molecule below is two days old and one molecule above in not yet sedimentary rock? How many inches, feet, miles "change" per day?
You see where I am coming from?
@ Green Star
What kind of farmers have you been hanging out with? I've been in farming my entire life and through 6 states and never heard of such a thing... I've known quite a few myself and never heard of anything like that from them either.
As a matter of fact, the only thing I've seen farmers do as far as interacting with worms is farm them to get MORE of them... and then to dump right onto their fields.
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The phrase "older than dirt" would mean soil to most people. The phrase is from agrarian people who used the word dirt to mean the soil they worked every day. Dirt being that soil that was not in it's place. Dirty pants, dirty floor. Take the context of the phrase for meaning.
Not really. In ordinary usage, an object's age is the amount of time passed since it was something fundamentally different. So the 'age' of sedimentary rock is how long it has been since the sediments were glued together, but the age of one tiny dust grain within the rock might be far older - it would be the time when that grain solidified from lava. A single sedimentary stone might contain pebbles and bits of wildly different ages.
Similarly, the aluminum in your car formed when a star exploded and made the elements. But that doesn't mean that you car is 10 billion years old.
12/19/09 at 7:51 pm
if the earth were to instantly stop spinning what would happen?
Imagine every molecule of your body separating in different directions at the speed of light.. That, Igon. is why we don't cross the streams....
Oops, wrong scenario...
The massive g-forces upon all constructed and natural materials would experience a lateral sheer of, well depending upon your latitude, would vary but as Wiki states:
The angular speed of Earth's rotation in inertial space is (7.2921150 ± 0.0000001) ×10−5 radians per SI second (mean solar second). Multiplying by (180°/π radians)×(86,400 seconds/mean solar day) yields 360.9856°/mean solar day, indicating that Earth rotates more than 360° relative to the fixed stars in one solar day. Earth's movement along its nearly circular orbit while it is rotating once around its axis requires that Earth rotate slightly more than once relative to the fixed stars before the mean Sun can pass overhead again, even though it rotates only once (360°) relative to the mean Sun.[n 4] Multiplying the value in rad/s by Earth's equatorial radius of 6,378,137 m (WGS84 ellipsoid) (factors of 2π radians needed by both cancel) yields an equatorial speed of 465.1 m/s, 1,674.4 km/h or 1,040.4 mi/h. Some sources state that Earth's equatorial speed is slightly less, or 1,669.8 km/h. This is obtained by dividing Earth's equatorial circumference by 24 hours. However, the use of only one circumference unwittingly implies only one rotation in inertial space, so the corresponding time unit must be a sidereal hour. This is confirmed by multiplying by the number of sidereal days in one mean solar day, 1.002 737 909 350 795, which yields the equatorial speed in mean solar hours given above of 1,674.4 km/h.
The tangential speed of Earth's rotation at a point on Earth can be approximated by multiplying the speed at the equator by the cosine of the latitude. For example, the Kennedy Space Center is located at 28.59° North latitude, which yields a speed of: 1,674.4 kilometers per hour (1,040.4 mph) × cos (28.59) = 1,470.23 kilometers per hour (913.56 mph)
So, to summarize , taking in the rotational speed of the earth at various latitudes, the effect will cross the realms of between coastal flooding, sheered crust, instantly accelerated buildings and topography to 1k Mph. to a shake and shiver at the poles. but watch out for the cross wind!
So, to sum it up... very bad things.
حقا هذا هو الصحيح. allanboerger@
Aww Jefro, you beat me to "older than dirt" lol
*kneels to pay respects to Jefro*
@extremechiton I think that if the world suddenly stopped spinning life would come to an end period. Hopefully that will never happen.
LIFE IS TOO SHORT.
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