We made it as far as the top of Yell only to find out that there were no boats to Unst. I had been hoping to find rocks from the Shetland Ophiolite Complex there. Here's the view from the ferry port towards Unst.
The rock below came from the end of the pier at Gutcher on Yell. You could see the ophiolite rocks across the water. There were superficial similarities - I was optimistic.
Unfortunately closer examination suggests that it is a type of schist - layers of crystals. It was not bedrock so it could have come from anywhere in the vicinity - but probably not Unst!!
