This picture is on slate, a support not uncommon in seventeenth-century Italian landscape paintings. Slate offered an economic alternative to copper or panel, though by its nature it determined small dimensions.
This is a variant with some differences of a signed and dated picture on canvas recorded with Colnaghi (A. Busiri Vici, Peter, Hendrik e Giacomo Van Lint, Rome, 1987, p. 107, no. 103, illustrated p. 106).