Here's what I was going to have above the lower level

But, then I got thinking about what would happen if I had a derailment under the upper level. I'd have to get a wee grandchild to retrieve my train! It was also going to have a severe incline in a relatively short distance. Not good.

So, back to the drawing board.
I made a stand-alone yard that would be higher than the lower level, but would give me about 23 feet of travel to go up 7". I think that is do-able.  Here's where the tracks will cross the "old sink-hole" and start the journey down to level ground.
The next photo shows the track making a big curve to cross over the lower level.  A truss bridge is in place, and some rock faces will cover up a bit of the lower level, but not enough to cause me any problems.
Lower level starts the incline to the upper level.
The lower level connects to the upper by way of a new crossover.  A train arriving from the "peak" will be able to go through a "reverse loop" and cross over to the lower level and have running rights.
The next picture shows the reverse loop.  I hope that this design will allow hours of enjoyment!