Here's some of the carvings. This first on shows a rider on a horse and some footprints. The stones are covered with pictures of shoes, ovals with a line through them showing the strap that holds them to the foot. There are many theories about what the feet mean, from as simple as an individual leaving their mark (a permanent footprint) to as far-fetched as a representation of gods of the underworld walking on the other side of the stone and we can see only the bottoms of their feet. As appealing as that idea is, it's probably just the Bronze Age equivalent of carving your initials.
This second one shows a procession to a line of boats. The carvings are reddish because at one point they had been painted, but they found this makes them erode faster. Also on the site was a replica of a Bronze Age building. We were very pleased with this visit – we hadn't expected much and were very surprised with how much this area offered.