About 3,200 BC sea-level was only about a metre below present, meaning that sea water had yet to penetrate into the Loch of Stenness. The loch existed as a smaller body of fresh-water, bordered by a reed beds that led on to a rocky shoreline. To the east the rocky outline of high ground would define the ridge that would later become the Brodgar Peninsula. On the far side lay a boggy area of peatlands, where the loch of Harray now lies.
Those who first chose this area to build the monuments such as the Ring of Brodgar knew a very different landscape to that of today. Unknowingly they had selected the very area that would be one of the last to remain vulnerable to change on a grand scale. As their monumental complex developed occasional storm surges would bring salt water into the loch of Stenness when seawater overtopped the rocky barrier at the Brig of Waithe. This must have been a spectacular event, all the more so because with time the waters of the loch rose, the loch of Harray gradually flooded and the ridge that separated the two lochs would get smaller and more pronounced. Increasing salinity would also alter the surrounding vegetation here.
We do not know how the communities to whom this was a special heartland reacted, but we can be certain that they would have been aware of the changing landscape and concerned for the future of their sites. Perhaps the emphasis of archaeology along the ridge today reflects that.