The oldest SANFL Club is?

From the SANFL Website we read the following on the South Adelaide history page,
South is the second oldest football club in South Australia.
http://www.sanfl.com.au/clubs/south_adelaide/
On Wikepedia however the following information is found,
The Port Adelaide Magpies Football Club - "the Magpies" - was founded in 1997 to replace the original Port Adelaide Football Club
http://en.wikipedia.org/wiki/Port_Adelaide_Magpies
So which website is correct? Is South Adelaide the oldest club in the SANFL or is Port Adelaide the oldest club in the SANFL?
South is the second oldest football club in South Australia.
http://www.sanfl.com.au/clubs/south_adelaide/
On Wikepedia however the following information is found,
The Port Adelaide Magpies Football Club - "the Magpies" - was founded in 1997 to replace the original Port Adelaide Football Club
http://en.wikipedia.org/wiki/Port_Adelaide_Magpies
So which website is correct? Is South Adelaide the oldest club in the SANFL or is Port Adelaide the oldest club in the SANFL?