Since the late 70s there has been a lot of work done to bring sand back to New Brighton. Part of this involved building groins out into the river. These catch sand causing it to build up. The groin near the bottom of Caithness Drive is behind Jane. It's working so well the sand now stays clear of the river water unless the tide is exceptionally high.
The strong wind on Thursday was blowing the dry sand in all manor of strange patterns. This image doesn't really capture the effect. I took a short video that is better.