Cara Dufour Denison in The Thaw Collection: Master Drawings and Oil Sketches, Acquisitions Since 1994. Exh. cat., Pierpont Morgan Library. New York, 2002, pp. 224–25, no. 104, ill. (color), notes that the rocks and tree trunks depicted here could have been compositional elements in a larger work and that the blue paper on which they appear suggests that the sketch was made outdoors and later mounted on canvas; compares it to another sketch by Lear in the Forbes Magazine Collection, New York, a study from four years earlier executed at Corpo di Cava, near Naples, though indicates that Lear spent the summer of 1842 at Monte Casale in Sicily; states that in both studies the artist seems to be looking back to his ornithological and animal studies of the 1830s.
John Gage. "Addressing the Outdoors." Studying Nature: Oil Sketches from the Thaw Collection. Ed. Jennifer Tonkovich. New York, 2011, p. 26, fig. 22 (color), notes Lear's self-criticism regarding the lack of dark colors in the oil sketch, permanently captured in his inscription at upper right.
Esther Bell. "Catalogue Raisonné of the Thaw Collection." Studying Nature: Oil Sketches from the Thaw Collection. Ed. Jennifer Tonkovich. New York, 2011, p. 132, no. 93, ill. (color), calls it "Study of Rocks, Shrubs, and Tree Trunks at Monte Casale near Sansepolcro, Tuscany".