Dawn's Rock Deterioration Page

This page provides illustrations of a range of different types of deterioration observed in different rock types, at both micro and field scales.

Deterioration of excavated rockslopes

The photographs shown below illustrate the key modes of excavated rockslope deterioration observed in the field. These are further explained and classified in the paper "Excavation-induced deterioration of rockslopes" by Nicholson, Lumsden and Hencher (2000).

1a: Rockfall debris on the M6 cuttings in metamorphosed Silurian turbidites at Tebay

1b: Palaeo-weathering (dissolution) profile exposed after quarrying in limestone.

1c: Stress release fracturing in uppermost part of old gritstone quarry face

1d: Frequent, low magnitude release of chalk blocks from a highway slope - stone ravelling

1e: Depositional lobe from rock mass collapse in blast shattered limestone

1f: The so-called 'root wedging' effect from a mature tree in weak sandstone.

1g: Micro runnels and solution pitting caused by groundwater seepage in limestone

1h: Incipient corestone development in sandstone due to penetration of chemical agents

1i: Penetration of small woody stems into fractured rock - what came first, fractures or roots?

1j: Accumulation of deposits in wide aperture fractures due to granular disintagration of coarse sandtone on fracture walls.

 

Micro-deterioration of rocks after experimental weathering

The SEM images shown below illustrate different forms of deterioration observed at the micro scale, following periods of experimental weathering by freezing and thawing and salt weathering. Further explanation is given in the paper "Physical deterioration of sedimentary rocks subjected to experimental freeze thaw weathering" by Nicholson and Nicholson (2000).

SEM image of high density chalk

SEM image of high density chalk

2a: SEM micrograph showing en echelon fracturing in a high density chalk due to experimental salt weathering

2b: SEM micrograph of salt weathering induced, blunt-ended cracks of varying aperture in a high density chalk

SEM image of weathered sandstone

SEM image of weathered sandstone

2c: SEM micrograph showing magnesium sulphate salt deposits on detrital grains in a weathered sandstone following experimental salt weathering

2d: Backscattered SEM micrograph of brittle intragranular fracturing in a weathered sandstone due to salt weathering

SEM image of micaceous sandstone

SEM image of micaceous sandstone

2e: Backscattered SEM micrograph of en echelon cracks in a micaceous sandstone, induced by salt weathering

2f: SEM micrograph of salt weathering induced cracking leading to linking of pre-existing pores

SEM image of magnesian limestone

SEM image of laminated siltstone

2g: SEM micrograph of transgranular cracking induced by experimental freeze-thaw in a highly porous magnesian limestone

2h: SEM micrograph of freeze-thaw induced irregular, en echelon cracking in a closely laminated siltstone

SEM image of low density chalk

SEM image of high density chalk

2i: SEM micrograph of 'fracturing' in a low density chalk due to pore alignment

2j: SEM micrograph showing large scale surface scaling due to freeze-thaw in a high density chalk

Copyright 2003: Dawn T. Nicholson

If you wish to use any of these photographs please just let me know.