First Steps in Limestone Weathering and Erosion: An Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) approach

A combined atomic force microscope (AFM) and scanning electron microscope (SEM) experiment examining the first steps in limestone weathering and erosion is presented. The experiment deals with the exposure of polished limestone rock tablets to a Western Mediterranean coastal environment and with the rate and patterns of weathering addressed by roughness quantification and qualitative assessment of nanoforms. Observations show how rock surface roughness increases at high rates after four and six months of exposure, passing from initial roughness RMS values between 14 and 32 mm to values between 396 to 492 mm. From the qualitative SEM approach, it can be concluded that the roughness increase relates with the widening of the space between rock grains and results in the isolation and detaching of rock grains