[AccessD] Does a directory exist?

I've been playing around with the Dir() function but I can't figure out how
to determine whether a directory exists, so I can create it if it doesn't.
Followup question: can I create a directory called "C:\major\minor" if
"C:\major" doesn't exist, or do I have to create "C:\major" first and then
create "C:\major\minor"?

TIA,
Arthur