Along the western coast line of Dorset between Weymouth and Bridport is a high ridge formed (if I read the geological map correctly) of chalk and limestones. Behind Portesham there is a gap, or valley, in the ridge and this forms the National Nature Reserve called the Valley of Stones. This, according to the Natural England information for the site, "is considered to be one of the finest examples of a Sarsen stone boulder train in Great Britain. Freeze/thaw conditions at the end of the last ice age caused sandstone on top of the nearby chalk hilltops to fragment and slump downhill." The site is not only of natural interest and geological interest but of historic interest too with links to megalithic times.
To the casual observer there does not appear to be much to see other than fine views along the Dorset coast. The boulders, though, are covered in lichens, some of which are very rare. The grass is somewhat rough and ready and I did not find much of interest although there is a good colony of Adonis blue butterflies here apparently. What I did find interesting (but then I suppose I am a bit odd) is that despite this being chalk and limestone when I analysed the plants I found there were a good number associated with acid soils rather than alkaline calcareous soils. I am sure there is a good reason for this but as I am no expert I have no idea why!
Being some distance from my home and being heavy going under foot I have not really given this site the attention it deserves; I must do better.