The marks that are beside the red cross, in the image, are flaws in the rock - perhaps where fossilised shells have lain. The round hole, in a couple of the pictures, has been carved however. I don't know why these holes were made and there has been an explanation that they were used for capturing spirit in sorcery. Here's one in south Northumberland (http://www.themodernantiquarian.com/post/48610). It's a pity the Rock Art goolies ignore these - but they do ...