Ford marveled again at the strange temperature. He'd heard tales of a mine to the far West that had run afoul of underground volcanic activity. The tunnels had become heated and full of steam before the miners had evacuated.
That mine had been abandoned for its dangerous nature, but there were others like it to a lesser degree. As long as magma chambers weren't breached, there was usually time to get everyone out.
"When you were here, those years ago," Ford asked Gary, "Was it this warm?"
"No. It must be a seasonal change," Gary lifted a hand to brush him off.
"Underground doesn't have seasonal changes," Ford argued. "Everything stays within a few degrees temperature all year round, no matter what is happening on the surface. Besides, isn't it fairly chilly right now? We're heading into summer, not coming away from it. If anything, there should be leftover cold, right?"
Do you remember the 21st night of September?