Isabel knelt and reached out hesitantly to touch the mark, nodding and frowning.  "It is cold.  How strange."  She held the light at different angles, tilting her head as she studied it.  "It must have been something quite heavy indeed," she mused.  "And sharp, perhaps?  Yet it does not seem to have been done purposefully.  What could have done this so carelessly?"<br/><br/>As she moved the beam, she caught sight of a similar mark on another patch of exposed stone some distance away and gestured to it.  "The caves are in that direction, and not very far from here.  It must have gone there... whatever<em>it</em>might be.  Perhaps we have a great many visitors here not of this time," she added, hiding a shiver.  Though she would sooner have died than admitted anything of the sort, the closer they drew to the caves the more her nerves troubled her.  If the enemy was something as inexplicable to her as the Doctor and his ship, then her bow and arrows -- not to mention all her determination -- suddenly seemed an empty, foolish gesture.