Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 25 Part 2: 66-72 - July 1963

A publication of the National Speleological Society

Canga Caves in the Quadrilátero Ferrífero, Minas Gerais, Brazil
George C. Simmons

Abstract

Unusual types of caves have been found in the Quadrilátero Ferrífero of Minas Gerais, Brazil. The caves occur where metamorphosed Precambrian sedimentary rocks have been eroded from beneath a resistant cover of Cenozoic canga. The caves can be divided into two classes, solution caves and corrasion caves, accoridng to the kind of erosion responsible for their formation. This, in turn is dependent upon the lithology of the rocks, the solution caves being in itabirite, and the corrasion caves in phyllite and schist. Many solution caves are multichambered and have linear extents of over 100 meters. The corrasion caves are single chambered and are not known to have lateral dimensions greater than 15 meters.

Leucophosphite, a rare phosphate mineral formed by the action of organic solutions derived from bat guano with iron oxides, was discovered in one of the caves.

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