London: Corgi Books, 1988. 192 pages.
Before Terry Pratchett's career took off with the wildly popular Discworld series, he wrote Strata. Intended as a pastiche of Larry Niven's Ringworld, it also amusingly explores the Omphalos hypothesis: "Discovering two of her employees have placed a fossilized plesiosaur in the wrong stratum, not to mention the fact it is holding a placard which reads 'End Nuclear Testing Now', doesn't dismay the woman who built a mountain range in the shape of her initials during her own high-spirited youth. But then come a discovery of something which did intrigue Kin Arad. A flat earth was something new..."