A Silhouette
As he gets closer to the ice wall, he puts light on it. The light moves over the dark silhouette, but he can’t really see anything or get a clue as to what it was. He knew he had to try something else, and he thinks he has just the item to do it.
No Luck
Mark searches through his few supplies and comes out with a pickaxe, starting to chip at the ice. However, it’s quite solid. He worked for a long time but realized he’d made little progress. Unfortunately, he might freeze to death before he got to the core.