Rhiannon's entry* quotes that, "Near the River Kennet in this shire, there breaks out water in the manner of a suddain Landsflood, out of certain Stones standing aloft in open fields, which by the common people is accounted a fore-runner of death."
The Landsflood certainly sounds like the water meadows between the Kennet and Silbury, as shown in your photo. Perhaps the, "Stones standing aloft in open fields" is referring to the stones of West Kennet Long Barrow - that might explain why the flood, and the stones standing aloft, were seen as a fore-runner of death.
