Subject: Why are the grains of sand so uniform in size?

Any beach, any land, seems to always have the same basic size
grains +/- a little. Where does the super small stuff go? It must
be somewhere. There seems to be a lack of this super fine dust -- 
does it end up at the bottom of the oceans? 
After hundreds of years, whouldn`t millions of waves
grind the sand on a beach to dust?  And where are all the large sand 
grains, before they get smaller? I just think sand is weird!

Re: Why are the grains of sand so uniform in size?