The geological forces that created The Three Sisters are revealed in Paul Gorjan's book, Geology of the Blue Mountains: A Tourist's Guide. Thebook was launched at Leura Uniting Church on August 11.
My background's in geology so obviously I was interested in the rocks around here, they're a big attraction.
His book offered insights into the science of the valleys in the landscape.
As Gorjan writes: "The Three Sisters was formed by the same processes that formed the rest of the Jamison Valley; softer layers of claystone were eroded and the harder sandstone on top tilted and then broke away along joint planes."
"I moved up here four years ago," he said. "My background's in geology so obviously I was interested in the rocks around here, they're a big attraction .. a lot of tourists come up ... whether they know it or not, to see the geology.
"I couldn't find any book that was available," he added.
"I did find a few technical reports but they're not readable for the average person."
Mr Gorjan has had a research career in earth science. He was awarded a post-doctoral fellowship from the Japanese Society for the Promotion of Science to work on the study of mass extinctions at Tohoku University. He also worked as a research scientist at Washington University in St Louis.
Mr Gorjan's talents also extend to art. He was a finalist for the Gallipoli Art Prize in 2018 and did the diagrams in the book.
"Learning for me is consolidating my knowledge," he said.