June 11, 1912–April 2, 2000
BY PAUL BARTON
HAROLD LLOYD JAMES IS widely recognized for his trail-blazing interpretations of the field relationships and petrology of the metamorphosed and structurally complex iron-rich sedimentary rocks known as “iron-formation.” Although James focused his research primarily in northern Michigan, the fundamental interpretations he made there have proven applicable worldwide, and northern Michigan has served as the archetype of sedimentary iron deposits that constitute the bulk of the world’s iron ore resources. He is broadly acknowledged to have been a world leader in this scientifically and economically important subject.
Prior to James’s work, the unusual chemical and mineralogical character of iron-formation was attributed to metamorphism and hydrothermal alteration of iron-rich carbonate sedimentary rocks. James peered through the veil of metamorphism and subsequent local oxidation, unraveling the spatial relations among rock types, deciphering their primary igneous and sedimentary patterns, understanding their structural and petrogenic affiliations, and showing that the iron-rich assemblages of rocks exhibit a systematic and oft repeated sequence of intergradational facies that reflect the integrated sedimentary environments in ancient ma-