ACTA ACADEMIAE ABOENSIS 
MATHEMATICA ET PHYSICA I:4 
ON THE 
LITHOLOGY AND GEOLOGICAL STRUCTURE 
OF THE 
SIERRA DE UMANGO AREA, 
PROVINCE OF LA RIOJA, ARGENTINE REPUBLIC. 
A CONTRIBUTION TO THE KNOWLEDGE OF THE SUBANDEAN 
BORDER OF THE STRUCTURAL ELEMENT OF THE 
„SIERRAS PAMPEANAS“. 
BY 
H. HAUSEN, PH. D. 
ÅBO AKADEMI 
ÅBO 1921 
