Climb the ladder, and grab the last treasure. Take a running jump across the crevasse, then Indy will face one more jump. Indy will have to drop down and walk through the gap. After conversing with Sophia Hapgood, Indy's off on his adventure. This was the easy level.
Many more adventures are to come.
Afterall, if adventure has a name, it must be Indiana Jones. Net is not part of, nor associated directly with LucasArts in any way.