AG Pool lost almost all its water, time for a new liner

Was getting ready to prep my pool for this season and as I removed the cover, I noticed that I only had about half a foot of water left on the bottom. Looks like I have a big enough leak somewhere towards the bottom. I'm not sure how long the water's been at that level, but I'm pretty sure the liner is shot and needs to be replaced.

Problem is, I'm not exactly sure what kind of liner this is, as it doesn't look like the kinds that the guides show you for overlap, beaded, or unibeaded. Further, I measured the height from top of the liner to the bottom of the pool at about 2 feet from the edge and it's showing up around 49 inches (shouldn't it be 48 or 52?)

Here are some pictures that I thought might help to identify - I'd appreciate any info that anyone might be able to provide.

http://i.imgur.com/nfKiC.jpg
http://i.imgur.com/YEyzi.jpg
http://i.imgur.com/rCY5w.jpg
http://i.imgur.com/tWMBn.jpg

Thanks!