SOLVED. Adult Sci-Fi. Alternate reality - a civilization evolves in a large cavern. "Space" for them is solid rock. An adventurer builds a tunneling machine and digs to find other caverns. [s]

[Radclyffe]

I recall a key plot line being that people doubt that other cavern worlds exist and the adventurer has no way of knowing if they are heading towards one or just getting stranded in solid rock

[David]

Hi, there.

When did you read this? A range of years is fine.

Do you remember the cover?

[Bargle]

I think I read this several years ago, but I don't remember where. If anything comes back to me, I'll let you know. Rock civilization thread.

Never mind. I was thinking of something else.

[Lobstergirl, au gratin]

So we don't get confused, Radclyffe is the OP.

[Genesistrine]

The Ring of Truth by David Lake?

Though it sounds more like the short story Me and My Antronoscope from the collection The Knights of the Limits by Barrington J Bayley.

[Radclyffe]

SOLVED - and found - Genesistrine - amazing...thanks so much. I downloaded both of your suggestions....it was indeed the short story Me and My Antronoscope from the collection The Knights of the Limits by Barrington J Bayley which I have just enjoyed rereading.

I must have first read this book as a young teen, so almost 40years ago and obviously the central idea of a reality made up of seemingly infinite solid and finite space must have stuck with me although I didn't recall some of the other story elements such as it being a story within a story.

Thanks again - will now get back to reading the other short stories in the book to see if I recognise any other long lost friends