where do rivers come from?

nachos

wasn't able to find a geology forum around, so i thought i'd put i here!

my question is a simple one (read: stupid)

i'd like to know where rivers come from. i know alot of them come from underground water sources, but where do these sources originate? are there underground lake where rivers begin, and if so where do these lakes come from?

is it just that rainwater has seeped down through the earth and formed these water sources?

put me out of my misery if you can! appreciate anyone who can shed some light for me!

tink~lvs~ptr

*ping*


http://geography.about.com/

gibo_ie

well AFIK most rivers originate high up in mountian areas. The rainwater flows down the mountain to the lowest point, this area that takes the water usually has a very saturated land matter below it or one of rock which is impermiable (sp?). These rivers keep flowing toward the lowest point (i.e. sea level).

You are right that some start as natural springs being pushed up through the earths core from caverns ,where rainwater has seaped through the ground, by the earths pressure.

Hope this helps (i am not a geologist!! )

tink~lvs~ptr

*ping*


Rivers begin in mountains or hills, where rain water or snowmelt collects and forms tiny streams called gullies. Gullies either grow larger when they collect more water and become streams themselves or meet streams and add to the water already in the stream. When one stream meets another and they merge together, the smaller stream is known as a tributary. It takes many tributary streams to form a river. A river grows larger as it collects water from more tributaries. Streams usually form rivers in the higher elevations of mountains and hills.

Redshift

Here is another good explanation about how rivers are formed.

ISAW

Depends on what you mean by a river. There are also temporary lakes and rivers. a limnologist might "fill you in". Wadis in the desert i mean are they "rivers" when the rainy season begins? What about rivers of lava? Or rivers of ice? I assume you mean water rivers.

The source of the water can come from underground but ultimnately the water came from above. Now in the hadel period (the earliest geological period just after the Earth formed) the earth was very hot and covered in volcanoes. there probably were no oceans.

Now to have water you need hydrogen and oxygen. Hydrogen is the most plentiful element in the universe in fact 98.5 percent of out solar system is hydrogen and helium in about a three to one ratio. . Now oxygen is also quite plentiful (along with Carbon and Nitrogen the next three most plentiful elements primarily because of the way stars work with the original hydrogen and helium universe making these three later elements more abundant than any others). rocks (silicates) contain lots of oxygen.

The earth is not massive enough to hold onto hydrogen in the atmosphere like the Giant planets. So it needed hydrogen and oxygen combined together to arrive from somewhere (ice or water).

It is believed that big ice asteroid/comet objects formed in the outer solar system far from the Sun. these were attracted into the solar system by gravity. Most probably vapourised in the Sun. some were pulled into Jupiter or a Gas Giant. Others were trapped in orbit. some never left the cloud they originated in. Anyway over say a billion years enough ofnough of these struck the Earth to deliver the oceans and clouds.

And that is where the water came from that formed the rivers.