chmod 600 on a folder

[SoundTheSurrender]

I don't quite understand why I can't access or read files from a folder with chmod 600. Shouldn't I still be able to access it? my umask is 0022..

user11@lx:~$ chmod 600 udir
user11@lx:~$ ls -l
total 24
drwxr-xr-x 4 user11 student 4096 2007-09-14 19:20 330
drw------- 2 user11 student 4096 2007-10-03 15:19 udir <-- only has read and write permission
user11@lx:~$ cd udir
bash: cd: udir: Permission denied

EDIT:

Does it mean that folders require a x permission to do anything with them?

 

[Nothinman]

execute on directories is permission to set them as your current directory, you can still read the directory since you have read permission, i.e. 'ls udir' should work, but you can't chdir() to it.