Edited by Dava Sobel

When two rivers meet,

they sometimes hesitate to mix.

The murky sediment load carried by one

keeps its distance from

the clear blue-green of the other.

Each reflects the color

of the landscape it has carved,

sometimes with caution,

and sometimes with turbulence.

Steep canyon walls bear witness

and scars of the steady descent

of water molecules pulled by gravity,

eroding crystals and grains, thirsty clay particles

that tumble and drift in the flow.

The rivers emerge and meander

away from the rugged mountains

and toward each other,

beginning to unburden their loads.

The distinct paths become one,

and the denser stream ducks under,

hiding its sedimentary past

along the line of mixing,

where eddies test the waters.

Clouds and clarity

complement each other,

and, with time,

dispersion and blending

shift the current into balance.