Before his long stay in Italy, Jones painted a number of views of the River Wye in his native Wales. This one shows the area north of Monmouth on the country's border with England.
Cairns are piles of stones marking the summit of a hill or mountain.
Whenever a walker reaches the top, he deposits another stone to the pile to mark his visit. Before the existence of accurate maps and established pathways, such distinctive landmarks were important in helping travellers find their way across the countryside.