Erosion of road batters in chim shale, Papua New Guinea

Erosion rates have been measured by repeated surveys over a 2. 5 yr. period. Total erosion expressed as a rate of surface lowering reached 4. 6-7. 2 cm yr** minus **1. Comparison with other measured erosion rates indicate that the rates recorded for Chim shale are amongst the highest measured anywhere in the world. The results could have been predicted from general considerations known for more than a decade. Furthermore, erosion of Chim shale batters could easily be substantially reduced by revegetation. Clay shales similar to Chim shale outcrop in other areas of the Papua New Guinea highlands. These areas are also undergoing development: efforts to minimize such erosion could be considered at the design stage.