Sublime Nature in Tom Sawyer?

I'm not a 100% positive that the whole class is this far yet, but when Tom and Becky (along with classmates) proceed to the cave and end up missing. Although, I believe the cave stands as sublime nature because it parallels as a test to Tom's maturity. Furthermore, Tom will gain this maturity if he can guide him and Becky out of the cave because it will show bravery, heart, and wit. To me, Twain almost describes the cave as like a challenge to Tom, and almost like a test. I believe that sublime nature only comes up when it parallels with another character to reveal the reality that the character is facing.  It also seems to me that when pastoral nature is described, everything seems surreal, in sublime nature, not so much. I think you can tell the difference in the scenes because sublime nature is just more realistic with the person's surroundings while pastoral nature is romanticized.