Karen, I can't emphasize strongly enough that what you get from the young-earth apologists is not the correct view of geology. Yes we do find widespread layers being deposited today.
Lets look at the Morrison.
First it is NOT one single lithology. With this in mind, lets look at the northern half of the Gulf of Mexico, west of Pensacola's longitude, where I work. This region consists of around 230,000 square miles and only sands and shales are being deposited. If we go south along the Mexican coast another 80,000 square miles could be added before you run into an area of significant limestone deposition. The Gulf of Mexico basin is is a similarly widespread system as the Morrison.