Classic Dungeon Trivia

This picture is not from the module

Thought I would try something a little different. I'll post an excerpt from a classic D&D module, and we'll see if anyone can identify which module it was pulled from. Sometimes it will be from the adventure's background or a description of a memorable room or encounter. I'll stick with published TSR modules so I don't get too obscure. Otherwise, whats the fun?

I don't have any prizes for you other than a chocolate bar, but you'll have to come pick it up from my house cause my wife won't let me cross the street after dark. And now for our first except....

"Days ago, your group of adventurers joined a desert caravan. Halfway across the desert, a terrible sandstorm struck, separating your party from the rest of the caravan. When the storm died down, you found you were alone. The caravan was nowhere in sight. The desert was unrecognizable, as the dunes had been blown into new patterns. You were lost."