SPOILERS The Breaking/Guardians mission questions

Hi all,
I have a couple questions regarding the last couple missions and any clarification would be great. So at the end of mission 13, Locke meets up with John and co and Cortana teleports blue team to some location. At the end of mission 14, Cortana traps blue team inside a cryptum. At the start of mission 15, this cryptum can be viewed while riding down the elevator to the snowy landscape below. My question is, where did Cortana teleport blue team too. Throughout mission 14 we are constantly travelling up and are on forerunner devices that seem to be floating…above Genisis, inside Genesis, or where? Also, how does that cryptum get so far below Locke for the start of mission 15.

My theory is that Cortana teleports blue team inside of Genisis, somewhere towards its core, and that they are making there way towards the surface of Genisis again. This the cryptum is located near the surface of the planet, and as blue team is trapped inside, the cryptum is brought to the surface as seen at the beginning of mission 15. Does this make sense? Any other theories or explanations?
thanks guys and gals.