You can scroll through the list of contacts on your iPhone a number of way
Flick your finger on the list to scroll up or down,
Tap on one of the letters in the alphabet running down the right side of the screen to jump to contacts beginning with that letter.
The not so widely know option is to hold your finger on the alphabetical list, then slide up and down, you can now scroll through your contacts in a more controlled manner than by flicking your finger.