**7. Mechanical properties of ice and ice-rock mixtures**

Having thus indicated the importance, yet variability of ice/water/debris fluxes within mountain systems in the British Isles in Younger Dryas times we now need to consider what the effects might be upon the mechanical properties of the materials produced. This has been considered in several papers (Whalley, 2009; Whalley & Martin, 1992; Whalley & Azizi, 1994; 2003) and will not be elaborated upon here. Figure 4 illustrates graphically another continuum, of strength or flow of ice according to the content or dispersion of rigid rock particles.

We have to use present-day analogues and known rheological behaviour to interpret past deposits. Unfortunately, even the present day features may be in dispute. This makes interpretation of Younger Dryas DDAs even more problematic, hence even more to interpret past climate from such features.

Fig. 4. This indicates both the possible mixture models likely to have been associated with the formation of most discrete debris associations and their mechanical properties. Thus, from the bottom left, rock slopes may fail and provide rigid blocks, perhaps amassed as scree with air spaces. If water/ice is mixed with the particles the mass is still rigid until there is enough ice in the mixture to allow ice deformation (Azizi and Whalley, 1995; Whalley and Azizi, 1994).

that Norway, similar in a geology of hard old rocks, also seems deficient in rock glaciers and protalus lobes. Unsurprisingly however, present-day scree formation in Norway does seem

Having thus indicated the importance, yet variability of ice/water/debris fluxes within mountain systems in the British Isles in Younger Dryas times we now need to consider what the effects might be upon the mechanical properties of the materials produced. This has been considered in several papers (Whalley, 2009; Whalley & Martin, 1992; Whalley & Azizi, 1994; 2003) and will not be elaborated upon here. Figure 4 illustrates graphically another continuum, of strength or flow of ice according to the content or dispersion of rigid rock

We have to use present-day analogues and known rheological behaviour to interpret past deposits. Unfortunately, even the present day features may be in dispute. This makes interpretation of Younger Dryas DDAs even more problematic, hence even more to interpret

Fig. 4. This indicates both the possible mixture models likely to have been associated with the formation of most discrete debris associations and their mechanical properties. Thus, from the bottom left, rock slopes may fail and provide rigid blocks, perhaps amassed as scree with air spaces. If water/ice is mixed with the particles the mass is still rigid until there is enough ice in the mixture to allow ice deformation (Azizi and Whalley, 1995;

more active than in Britain because of more severe weathering conditions.

**7. Mechanical properties of ice and ice-rock mixtures** 

particles.

past climate from such features.

Whalley and Azizi, 1994).
