Jim loved his fossil hunting, but was by no means an expert. And this was something new to him. He tapped again at its edges, and was delighted by the tooth falling free. He lifted it.

“You must be made of damned hard material.” He turned it in his hands. “Some sort of dinosaur… probably aquatic.”  He stuck it in a pouch at his waist, looking forward to researching the find when he got back.

Granger stood slowly, and wiped his brow. It was even warmer now. There was some volcanic activity in this area, as this was a tectonic collision point, but mostly it was just the odd shimmy and shake from minor earth tremors. He shone his light up at the ceiling, but saw nothing to worry him in the cave structure above.

He crossed the huge room to then ease himself into another tunnel. As he turned sideways to wedge himself into the crevice, he noticed that some of the stones were raw, as though newly broken. He shone his light beam upwards again – there was a lighter patch on the ceiling – the rock had fallen recently. He exhaled, indecision freezing him for a second or two. In geological terms, fallen recently, could have meant any time in the last five minutes or fifty thousand years.

He shrugged and decided to press on, travelling ever lower. The going was easier, but the slope was getting steeper, and he knew he had descended quite far by now, and well below sea level. Even with a light pack, it would be a wearying climb back out. He stopped to mark some more chalk messages on the cave wall, and he would do so again at the change in the geology.

Minutes passed, and then more minutes. Granger knew he wasn’t being mindful of the time when he came to another split in a rock wall. He checked his wristwatch. Last one, he thought, aware now that he had exceeded his planned descent timing. He eased through, walking side-on for several uncomfortable minutes until he popped out the other side, and into another large chamber. He held the lamp up, and then sniffed – dampness, but not the damp smell of moss, mould or slime, but unexpectedly that of seawater. He walked slowly forward; his arm outstretched holding up the lamp. His foot kicked a small piece of rubble that bounced several times before disappearing into one of the numerous holes in the cave floor. He frowned, hearing the rock carry on bouncing as it continued its descent.

At the center of the cave floor there was one hole, larger than the rest. This one had what looked like the remains of a rope ladder still clinging to wooden pegs at its edge.