Hilltops surrounded by farmland in southern Wisconsin turn out to be the eroded remnants of an ancient archipelago. An island in the Yellow Sea where Korean tourists flock is the peak of a flooded mountain rising from a drowned continental shelf. From a mountaintop shrine to Genghis Khan in Inner Mongolia, the silhouette of a Silurian seascape can be spotted. On the shores of Hudson Bay, where polar bears patrol the Arctic tundra, a close look unveils what was a tropical coastline encrusted with corals nearly 450 million years ago.

The geologist Markes E. Johnson invites readers on a journey through deep time to find the traces of ancient islands. He visits a dozen sites around the globe, looking above and below today’s waterlines to uncover how landscapes of the past are preserved in the present. Going back 500 million years to the Cambrian through the Pleistocene 125,000 years ago, this book reconstructs how “paleoislands” appeared under different climatic conditions and environmental constraints. Finding vestiges of prehistoric ecologies, Johnson emphasizes the complexity of island ecosystems and the importance of preserving these significant sites.

Inviting and accessible, this book is a travelogue that takes readers through time as well as space. Islands in Deep Time shares the adventure of exploring striking locations across geologic eras and issues a passionate call for their conservation.

"[A…] geological tour de force." - Deposits Magazne

"Each of the twelve chapters includes a topographic map of the island's physical structure paired with a global map showing its location in the context of the geography unique to that time. The accompanying narrative offers a guided tour of each island, illustrated with images of fossil finds and geologic features." - Outrider Books & Travel

"Very much an enjoyable, informative, and relatable text that will serve well both the serious student of geology and the engaged lay reader alike." - H-Environment