Sort of a follow-up to the previous post...here is a National Park Service diagram of the Grand Staircase (click on the image to enlarge). The image has been a popular poster in the National Park Service Bookstores for years, and I was pleased to find it on Wikipedia.
Highly Allochthonous made a great point the other day when he commented about how easily we geologists can confuse laypeople when we start describing geological periods and eras without noting the actual years in which the events took place. I am taking advantage of a time scale that Chris provided on his website, and have added to the page elements to the left (scroll down). I hope it clears up any confusion!