He served as lecturer in Petrology at the University of Edinburgh , and as Petrographer ( 1901 ) , Assistant Director ( 1911 ) and Director ( 1920 -- 3 ) of the Geological Survey of Great Britain .
Flett worked as a general practitioner .
Flett served as lecturer in Petrology at the University of Edinburgh , and as Petrographer ( 1901 ) , Assistant Director ( 1911 ) and Director ( 1920 -- 3 ) of the Geological Survey of Great Britain .
Flett worked as a general practitioner .