The caverns below La Greche

Roscomboltin, who would love to be Rosco to his friends if he could make any, felt the rope slip. He fell in the utter darkness, panicking. The rope caught on something, jerked, and he bounced on the end of it. Something metallic shrieked, and he fell a couple more feet, jerking to a halt again. Then it was over, and he was swinging like a pendulum, his hands feeling for his hard-hat, trying to get its lamp working again.
He took the hat off and ran his hands over its ridged contours until he found the lamp housing. Then he pounded on it with the ball of his thumb. At first nothing, and then suddenly some broken connection somewhere was remade and a weak yellow light spilled out from the bulb. Relieved he shook it, and the light strengthened.
He put the hat back on and looked around. The nearby wall was a deep pink, reminding him of roses that he'd not seen since coming to the La Greche, but otherwise the cavern just opened out and there was only blackness wherever he looked. When he looked down, he was startled to discover he was hanging mere inches above the cavern floor. He swallowed hard, wondering how close he'd come to hitting it, possibly breaking bones or... or worse.
He unclipped and dropped the eight inches to the floor. It crunched, and when he rubbed his feet he realised that it was a gritty black sand on rock. He looked up, admiring the rose-hued wall again, and his smile slowly faded as he wondered where black sand could come from if the walls were this colour. Rosco put a hand out for the rope, and as he pulled on it it came free from wherever it had caught and fell, coiling noisily on the floor. He dodged aside; rope that long was heavy and he didn't want to be caught under it.
"Well, well," said a voice in the darkness. "A... visitor again. It has been... such... a long time." There was something suggestive in the voice, and Rosco thought it might be hunger.
"Who's there?" He turned slowly through a full circle, peering in the hopes of seeing the speaker, but never seeing more than empty darkness.
"Think of me as... one of the... fallen. Not unlike... you, ha, ha."
Rosco noted the strange pauses, wondering if the speaker was short of breath.
"Well met!" he said, not meaning it at all. "So, is there another way out then?"
"Not... ha, ha, not... that I've found."
"Looks like I'm climbing then," said Rosco, trying to sound cheerful. He didn't feel cheerful though; the hole he'd come down through was probably in the middle of the ceiling, not near the walls, and climbing to that, in near darkness, would be suicidal. But then, staying down here with this strange speaker also seemed suicidal, and at least climbing he could die on his own terms.
"Ha ha, you should look... around first. There are... ha, ha things you should... see."
"Things?"
"...Bones."
"I'm probably a better climber than them," said Rosco, but his confidence was ebbing fast.
"Did I... say they'd tried to cli...mb?"
The black sand. Rosco realised that there was more here that he needed to know about before he continued.
"OK," he said, trying to sound friendly now. "So, who are you? Can I see you?"
The light on his hat went out, plunging him into a darkness that was starting to feel oppressive.
"Ha, ha, ha," laughed the voice. "It would seem not!"