Petrographs are created by using liquid light and them exposing the medium. The great thing about liquid light is that you can put it on almost anything you want to. In her 2009 installation called Faces in Nature she used many different items from nature. She used feathers, leaves, oyster shells, wood and even pine cones. In her blog she said that in the spring of 2008 she "received a grant from the Northampton Arts Council to create an installation that united urban downtown with the green periphery around the city".
She began creating this link by taking photos of pedestrians on main street. This took the city side of her art work element. Then she printed these what she calls "naturegraphs" onto pine cones, fungus and more. she then placed these items back where she found them and "let them settle into nature". Then as the settles she photographed them and let them lay where they were.
This is where i got my idea of printing on leaves and then placing them back into the environment in which I found them. Although I used a different method then she did I still followed the same concept.