From doing a little research, it looks like the Gibbie shawl is not knit in the round, but it also doesn't have to be seamed, either.
I found this when I did a google search for 'gibbie shawl, knitting':
1) It's fairly easy to get something pretty satisfactory if you proceed like Gladys Amedro in (for example) the "Gibbie Shawl" in her book "Shetland Lace" - that is, start with the edging, as before; pick up the stitches and knit inwards, as before; but don't stop and knit a centre - just keep going until you have decreased all the stitches away.
So basically, if you just follow the directions as written, knitting back and forth, as you do the decreases it will bring the inner edges together and you'll end up with a square.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry