Streams, rivers, and soil formation, how did they come to be?

[tvanwho]

Just got to to wondering how streams and rivers formed on planet Earth? Why don't they run in straight lines vs curly cues and lots of bends? Why doesn't the ground soak up the water? Why in aerial photos do watersheds appear like tree branches merging into larger and larger branches and then a huge river, and not a bunch of straight lines?
I always wondered what dirt was too and where it came from? Nobody ever talks about this stuff. We all just assume an awful lot or take it for granted..I know I have.

-Tom V.

[N2Au]

Random chaos theory

[MK111]

Water by gravity seeks it's own level. Simply explanation is water can't run uphill but always downhill. So your aerial maps the curves and bends are caused by high and low areas of ground level and water is always flowing down hill. I am sure someone else can go into greater detail.
48 yrs ago on my first house I installed siding. I couldn't figure out how to go around the house about 200 ft in length with about 10 corners and come out level at the starting and ending location.
A carpenter showed me how to use a clear plastic water hose with water in it. Just marked the water level on both ends of the hose from corner to corner and ended up only off one pencil mark in height or about 1/32". Water seeks it's own level.

[overtheedge]

Then factor in the concept of "path of least resistance". Erosion not only affects softer rocks quicker, but also rock that has been cracked by tectonics. Add some sand and gravel to the water and you have liquid sandpaper.

Often a river follows a fault, creeks can follow fissures, etc. And limestone is real susceptible to chemical removal leading to karst topography.

Sooner or later, the eroded material gets deposited. If the winds hit the deposit before it gets altered, it can carry the silt for hundreds of miles before redepositing it. Glaciers can transport giant boulders hundreds of miles as well as act as giant bulldozers.

We can thank Canada for the US mid-west's deep silt-loam topsoil. Probably for Long Island and Martha's Vineyard moraine deposits too.

The nature of nature is change. Homo sapiens hates change. And sometimes these physical geologic occurrences are the result of catastrophism. 100 year, 500 year or (shudder) 10,000 year occurrences. Floods, volcanism, earthquakes, tsunamis and even enormous forest fires can precipitate erosional changes.

Chaos theory or shall we call it the "butterfly effect"; I don't buy it. All too fuzzy for me to call it a valid theory. Let's call it as it is, "The Sh*t Happens" theory. If you build it, it will break be it a shaker plant or a planet.

[Geo Jim]

The reason streams dont flow in straight lines is certainly due to underlying geology in many instances. But the main reason is too much energy caused by speed causes turbulence. Turbulent flow of water causes scouring of pools and stream banks. Given geologic time, a river can meander all over the place.
Geo Jim

[tvanwho]

So, the rotation of the Earth has nothing to do with stream formation? I thought I read somewhere about the Coriolis effect altho I can't recall just what that is ? And speaking of our planet rotating and such, why are the planets and our sun ball shaped and why are they rotating anyway? Seems they could have just been big motionless blobs in space with no atmospheres, like the asteroids ?

-T

[overtheedge]

If the Coriolis effect was a big factor in stream direction, the rivers on the east coast would look entirely different.

Clock-wise ocean currents in the northern hemisphere and counter clock-wise in the southern are an example of the Coriolis effect. However, terrain trumps Coriolis. Coriolis is just an old wife's tale when it comes to river direction and erosion.

And yes, I think I saw some write-up in Popular Mining about the Coriolis effect. I also saw several on other quasi-scientific matters too. I love to read science fiction. It might have some scientific basis, but the noun is still fiction.

[FedFire]

The coriolis effect only determines the direction a whirlpool will spin (not an eddy), it has no bearing on stream direction, otherwise all northern hemisphere streams and rivers would have a gradual curve in the same direction. Kind of like the curved flight path of a bullet. But again, the coriolis effect only acts on the bullet while it is not in contact with the phisical surface. Since water is in contact with the physical surface, coriolis effect has little to no effect. Since everything connected to the earth is spinning around the center of the earth at the same speed.


......I think......

[FedFire]

Soil is usually made up oh host bedrock that has decomposed dude to chemical degredstion, weathering, and erosion. Which, if it's sedimentary then it can vary widely and is determined by where the sediment came from. Then of course throw in plant material and that's all pretty common knowledge.

[tvanwho]

9 out of 10 wouldn't have a clue what dirt is or where it came from or why streams flow the way they do? Heck, us gold prospectors could probably win a pile of cash asking these questions at bars.
I ,for one, am glad Alaska is taking a pounding this winter, and sparing the rest of the country. My largest heating bill this winter has been under 35 dollars for my condo. I think we've had under 12 inches of white stuff this winter in Chicagoland. Gettin the itch to go dig....

-T