Ah! Do you mean this old rose bed here? This is the area where they kept porcupine / skunks and otter. Still can't remember those marmots being there though.. darn memory. lol
I think that's where they were but I'm not 100% certain. As far as I remember there were two similar enclosures (at least one divided into two) - do you agree? I lost my pen in the one in your picture in October! I had been sitting on the wall to eat my lunch, rushed off to the Sealion Centre and didn't discover the pen (which had been on top of my bag) was missing until I went to write the notes of my visit on the train home. That's the second pen I've lost in that rose bed! I should learn.
Yes, there was one that was divided into two. In your photo of the Marmots (attached with the one of Cuddles) there appears to be two stone walls? Wonder what they were..
You'll have to go and visit the Zoo again and retrieve those pens! lol