In this paper we present a mobile application, named PetroSketch, for supporting archaeologists in the classification and recognition of petroglyph symbols. PetroSketch is a virtual notebook enabling users to draw a petroglyph symbol on a white page, or by following the contour of a symbol captured with the camera, and to obtain its classification and the list of symbols more similar to it. The latter is performed by a flexible image matching algorithm that measures the similarity between petroglyph by using a distance, derived from the image deformation model, which is computationally efficient and robust to local distortions