In 1951, Thon received a grant from the American Academy of Arts and Letters.
He began painting in oil in a fairly realistic mode, but during his stay at the American Academy in Rome he discovered watercolor as a serious medium and began to loosen his style some.
Perhaps the major breakthrough for his painting came with the discovery of an abandoned quarry near his home in Maine.
Here he painted spidery trees with rectilinear slabs of granite interspersed, such as in Midnight Quarry.
[1] This article incorporates public domain material from websites or documents of the Bureau of Reclamation.