Quote Originally Posted by Yandor View Post
and eventually divided the river into 2 streams thus the fork
Pet peeve alert! Rivers almost never fork. They almost always merge.

(This is my own understanding - if wrong, PLEASE let me know!)

Water is lazy (kind of like me) and will almost always take the easiest route. This means that if a stream encounters an obstruction, it will go around it the easiest way possible. If the left channel is easier than the right channel, it will take the left channel. Not to say that rivers don't split around obstructions....they just usually end up rejoining on the other side, as the terrain allows (since both channels are trying to find the easiest route).

This is amplified taking erosion into effect. Once a river has an established channel, it is rare that it will create a new one, unless it suddenly finds an easier way. This is also why streams are more likely to join up...the terrain has to keep them apart, and if they get close enough the "higher" one will find the "lower one"'s channel and flow into it.

BUT - as I have found in the past, no matter what bizarre geomorphic anomaly you can imagine, it probably exists somewhere in the real world

-Rob A>