Today I am reminded of Barbara Hepworth

Today I am reminded of Barbara Hepworth, Jim and Helen Ede, Henry Moore and a smiling Seal. I always thought that the pebbles scattered along Hampstead Heath’s paths were riverbed stones brought on to the heath to define walkways and roads. However it seems they’re a natural geological feature of the area.
‘The paths of Hampstead Heath are covered with rounded and polished pebbles of amber, brown or black flint. Pebbles of this same type are to be found running through sand deposits resting on top of the chalk in Hampshire and Berkshire, especially the heathlands around Bagshot. It seems that a great river (The Great Bagshot River) laid down sands from Salisbury Plain, through Bagshot, reaching North London before flowing into an early North Sea.
https://www.ucl.ac.uk/earth-sciences/outreach/public-engagement/londons-geology/londons-geology-fieldwork/hampstead-heath/geology