accident, of course,--the breaking away of some of the earth, loosened
by rain and frost and wind. But this is an accident which happens
daily in hundreds of places around the shores.

Leaving the ocean, look now at this river in our neighborhood, and see
the slight muddiness which seems to color its waters. What from? Only
a little earth and sand carried off from the banks as it flowed,--very
unimportant and small in quantity, doubtless, just at this moment and
just at this spot. But what of that little going on week after week,
and century after century, throughout the whole course of the river,
and throughout the whole course of every river and rivulet in our
whole country and in every other country. A vast amount of material
must every year be thus torn from the land and given to the ocean. For
the land's loss here is the ocean's gain.

And, strange to say, we shall find that this same ocean, so busily
engaged with the help of its tributary rivers in pulling down land, is
no less busily engaged with their help in building it up.

You have sometimes seen directions upon a vial of medicine to "shake"
before taking the dose. When you have so shaken the bottle the clear
liquid grows thick; and if you let it stand for awhile the thickness
goes off, and a fine grain-like or dust-like substance settles down at
the bottom--the settlement or _sediment_ of the medicine. The finer
this sediment, the slower it is in settling. If you were to keep the
liquid in gentle motion, the fine sediment would not settle down at
the bottom. With coarser and heavier grains the motion would have to
be quicker to keep them supported in the water.

Now it is just the same thing with our rivers and streams. Running