Where does the name etheridge come from?

Hi my surname's Etheridge. As far as I'm aware it is an English surname dating before the Norman conquest. It means on-the-ridge suggesting the first Etheridge's lived on a hill or mountain and the named as been changed over time as those didn't know how to spell changed it to see fit. Any surname with -ridge on the end is probably an alternative to Etheridge

Regards