The Axiomatic Earth describes a condition in which techno-scientific modes of classifying the Earth become sites of political struggle. Looking at the Bolivarian revolution in Venezuela, I will show how an imprecision in procedures of heavy-oil classification allowed for a dramatic transformation of the nation’s politic and territorial projects: the difference between a classification of Venezuela’s hydrocarbon reserves as tar-sands and a classification that described them as heavy-oil, was narrated by the government of Hugo Chavéz as the difference between neo-liberal policies and revolutionary ones. In the context of an oil-based economy, this shift constituted a semiotic transmutation of the Venezuelan underground that was essential to the development of the Bolivarian project.