Purves initially qualified in medicine at the University of Edinburgh before joining the army and travelling as an army doctor.[1] He had spent a couple of years working for the Geological Survey in Scotland before joining the Yorkshire Museum in 1878. He was initially employed as a temporary assistant to the museum before being made permanent Keeper following the death of the sub-curator Henry Baines.[3] He resigned this post in 1880 following his appointment to the Geological Survey of Belgium.
In his subsequent geological career he is attributed with naming the Namurian; a stage in the regional stratigraphy of northwest Europe with an age between roughly 326 and 313 Ma (million years ago).[1]